发信人: asdf (变量), 信区: Unix
标 题: AIX FAQ (1-5) (转载)(转寄)
发信站: 紫 丁 香 (Tue Jul 7 02:45:35 1998), 转信
发信人: Leeward (AIX), 信区: Unix
标 题: AIX FAQ (1-5) (转载)
发信站: BBS 水木清华站 (Wed Nov 26 08:22:37 1997)
【 以下文字转载自 sys_discuss 讨论区 】
【 原文由 Leeward 所发表 】m
发信人: captain (车前草) on board 'unix'
标 题: AIX FAQ (1-5)
发信站: 国家智能机中心曙光站 (Wed Nov 12 16:10:22 1997)
Frequently Asked Questions about AIX and the IBM RS/6000
__________________________________________________________________
This posting contains frequently asked questions and answers about the
IBM RS/6000 series workstations and AIX versions 3 and 4. All input is
very welcome, I can be reached at frank@prodigy.com.
The list is split into five articles to pass thru most mailers. I'll
usually try to post them once a month to comp.unix.aix, news.answers,
and comp.answers. Please let your input continue as I am most thankful
for all of it.
This FAQ is available from (see section 6.08 for more sites):
<http://www.emerson.emory.edu/services/aix-faq/>
<ftp://rtfm.mit.edu:/pub/usenet/news.answers/aix-faq/part1>
<ftp://mirrors.aol.com:/pub/rtfm/usenet-by-hierarchy/comp/unix/aix>
Please make a note of the fact that these sites contain more than just
the AIX FAQ and would probably be worth consulting before you post
questions to any of the usenet groups.
If you see a From: line it means that whatever follows is either an
unabridged or slightly edited version of the input I have received, and
that I may not have verified its contents. If there is no From: line, I
probably know what I am talking about, and the entry is edited from
various sources.
All entries are numbered with major and minor subject number, e.g.
2.11. If the subject is preceded by an asterisk, that entry has been
changed or added since the last posting.
The comp.unix.aix group is for AIX on all IBM platforms -- RT, PS/2,
370, RS/6000 and mainframes (ESA based on OSF/1), but the traffic has
evolved to discuss predominantly AIX 3.x, 4.x, and the RS/6000. The
newsgroups comp.sys.ibm.pc.rt and comp.sys.ibm.ps2.hardware cover the
RT, mostly hardware and AOS 4.3, and on PS/2 hardware respectively.
Mark Whetzel posts FAQ lists about RTs in the rt and *.answers groups.
There are few to non-existent discussions on AIX/370 and AIX/ESA.
If you post questions to comp.unix.aix, please be sure to indicate:
- the machine type and brief configuration, e.g. Model 540, 64 MB RAM,
48 MB swap space (this is actually bad), 1.2 GB XYZ hard drive, etc.
Note: There are now three classes of RS/6000s - the original, RS or
POWER, RS/2 or POWER2, and PowerPC.
- the exact AIX version number, i.e. AIX 3.1 is NOT sufficient, whereas
AIX 3.1.5 or AIX 3.1 with the 3005 update is. With 3.2 you should
mention any significant ptfs using the U4xxxxx numbers. With 4.x,
please mention any significant APAR numbers.
I am doing this on my own time. PLEASE DO NOT ASK ME QUESTIONS THAT
THAT SHOULD BE ASKED OF IBM. If you suspect you have software defect problems
call (800) 237-5511. If you have hardware problems call (800) IBM-SERV.
If you are outside the United States, contact your local IBM representative.
PLEASE DO NOT ASK ME QUESTIONS THAT SHOULD BE POSTED TO comp.unix.aix.
I don't have the time to diagnose individual AIX problems, and I
probably don't know the answer either. ;-) Many experienced and
knowlegable people read the newsgroup. Post your question there.
------------------------------
Table of contents:
1.0 General concepts
1.000 The AIX operating system - what is it?
1.001 I know neither Unix nor AIX - where do I find more information?
1.002 What is the Object Database?
1.003 How do I get rid of the verbose error messages?
1.004 Which release of AIX do I have?
1.005 What hardware do I have? What is availible? WITS?
1.006 Is IBM "dropping" AIX?
1.1 SMIT, system administration
1.100 I am used to Unix systems programming, why should I learn SMIT?
1.101 How do I turn off the "running man" in smit?
1.102 How do I import an /etc/passwd or /etc/group file from another box?
1.103 Cleaning up utmp, who, and accounting problems
1.104 How to fsck the root filesystem
1.105 How can I unmount /usr to run fsck on it?
1.108 How do I see/change parameters like number of processes per user?
1.109 How do I shrink the default paging space on hd6?
1.110 The swapper seems to use enormous amounts of paging space, why?
1.111 How much paging space do I need?
1.112 How do I mount a floppy disk as a filesystem?
1.113 How do I remove a committed lpp?
1.114 How can I recover space after installing updates?
1.115 Where are the AIX log files kept?
1.116 How can I log information about ftp accesses to a file?
1.117 How do I find a file name from the inode number?
1.118 How do I set up postscript accounting?
1.119 How do I create boot diskettes?
1.120 Where can I find tools for performance monitoring?
1.121 How can I tell what virtual printer a print queue is using?
1.122 Two srcmstr's are less useful than one?
1.123 How do I set the tty name associated with a physical port?
1.124 How do I use mksysb to clone a system?
1.125 How do I retain timestamps with mksysb?
1.126 How can I find out the machine type?
1.127 Updating to 3.2.5
1.128 AIX fix strategy
1.129 Are passwords limited to 8 char?
1.130 How do I increase the number of ptys > 64?
1.131 CERT advisories on sendmail and xterm
1.132 How do I remove a non-existant physical volume?
1.133 How do I kill a process that ignores kill -QUIT -KILL -STOP?
1.134 How can I see "console" messages?
1.135 Where can I find TOP for AIX?
1.136 How can I restrict root logins to specific terminals?
1.137 How do I merge my /etc/password and /etc/security/password for Crack
1.138 I lost the root password, what should I do?
1.139 How can I resolve DEV_WAIT status for a local print queue?
1.140 SMIT problems forcing/overwriting install?
1.141 Which distribution tape do I have?
1.142 How can I get PTF (fixes) via ftp? What is fixdist?
1.143 Is there an easy way to determine if AIX has a PTF applied or not?
1.144 How do I recreate a deleted /dev/null?
1.145 What is a checkstop error?
1.146 How do I recover deleted files?
1.147 What questions are on the AIX Certified User/SystemAminstrator/etc.,
exam?
1.2 Backups, tape
1.200 Some info about tape backups
1.201 How do I do remote backup?
1.202 How do I backup a multi-disk volume group?
1.203 How do I put multiple backups on a single 8mm tape?
1.204 How can I make an exact duplicate of a tape over the network?
1.205 What is tape block size of 0?
1.206 Resetting a hung tape drive...
1.207 How do I read a mksysb tape with tar?
1.208 How do I read a 5Gbyte tape on a 2Gbyte drive?
1.209 What can Sysback do for me?
1.210 How can I get my HP 4mm DAT to work?
1.211 How do I copy DAT tapes?
1.3 Memory and process management
1.300 Some info about the memory management system
1.301 How much should I trust the ps memory reports?
1.302 Which simms do RS6000's use?
1.303 What is kproc?
1.304 How do I create a RAM disk in AIX?
1.305 How much RAM (real memory) does my machine have?
1.306 Why do PIDs run non-sequentially?
1.4 Shells, commands, man pages, InfoExplorer
1.400 How do I make an informative prompt in the shell?
1.401 How do I set up ksh for emacs mode command line editing?
1.402 Listing files with ls causes a core dump
1.403 How do I put my own text into InfoExplorer?
1.404 InfoExplorer ASCII key bindings
1.405 How can I add new man pages to the system?
1.406 Why can't I read man pages? Where is nroff?
1.407 Why is my enviornment only loaded once?
1.408 Where is the 'nawk' command on my AIX system?
1.409 How do I copy InfoExplorer (manpages and more) to my hard drive?
1.410 Why can't I set my default shell to one we've just installed?
1.411 Why do I get the "Unable to connect socket: 3" starting Info-Explorer?
1.5 Video, Graphics, X11
1.500 Which release of X11 do I have?
1.501 How to prevent ctrl-alt-backspace from killing the X session
1.502 Who has a termcap/terminfo source for aixterm or the HFT console?
1.503 How can I look at PostScript files? Why is "dpsexec" so lousy?
1.504 unix:0 vs `hostname`:0
1.505 VT100 key bindings for aixterm
1.506 Is there a screen saver that does not use excessive CPU?
1.507 Where are the colors, availible for an X session, listed.
1.508 Why does my app hang the X server but not an X station?
1.509 How do I switch the control and caps lock key bindings?
1.510 Missing fonts?
1.511 What's the termcap entry for an IBM 3151 look like?
1.512 Errors starting X11 application binaries from aixpdslib.
1.513 .XShm*, .sm* (Shared memory) Link errors building Xwindows applications.
1.514 How do I set my DISPLAY when I login to another machine?
1.515 Why doesn't Netscape work?
1.6 Networks and communications
1.600 My named dies frequently, why?
1.601 How do I trace ethernet packets on an AIX system?
1.602 What is the authorized way of starting automount at boot time?
1.603 How do I set a tty port for both dial-in and dial-out?
1.604 How to move or copy whole directory trees across a network
1.605 How can I send mail to hosts that cannot be pinged?
1.606 How to configure dialup SLIP
1.607 Where is DCE discussed?
1.608 How do I make /var/spool/mail mountable?
1.609 getty spawning too rapidly
1.610 Does AIX support Compressed SLIP (CSLIP)?
1.611 How do I setup anonymous ftp on my AIX system?
1.612 Talk, getting notification.
1.613 Disabling software flow control; using RTS/CTS.
1.614 NIS security
1.615 Why can't non-anonymous users login using WU-FTP?
1.616 NIS users can't login, do I need '*' in /etc/passwd?
1.617 HP JetDirect cards and virtual printers? mkvirprt problems?
1.618 How can I hack libc.a to alter how hostnames are resolved?
1.619 What modem settings do I need?
1.620 NIS slave server config with master on different subnet?
1.621 Why does my 64 port concentrator loose data and drop the queue?
1.622 Netscape FastTrack server won't install on AIX 3.2.5 or 4.1.
1.623 How can I share files/printers with Windows 95?
1.7 LVM
1.701 How do I shrink /usr? (formerly 1.106)
1.702 How do I make a filesystem larger than 2Gb? (formerly 1.107)
1.703 Chlv warning, is the first 4k of a LV safe? (formerly 1.139)
1.704 What's the limit on Physical Partitions Per Volume Group?
1.705 Why am I having trouble adding another disk to my VG?
1.706 What are the limits on a file, filesystem?
1.707 Hints for Segate 9 GB and other disks larger than 4 GB? (see 1.704)
1.708 How do I fix Volume Group Locked?
1.709 How do I remove a volume group with no disks?
1.8 AIX 4.1
1.800 How do I control how hostnames are resolved?
1.801 dtlogin ignores /etc/profile?
1.802 Where's the C compiler?
1.803 Why doesn't Netscape work?
1.9 Miscellaneous
1.900 SCSI-1 and SCSI-2 "interoperability" got you confused?
1.901 How to get your keyboard back after unplugging it from the 6000
1.902 How do I set up pcsim, the DOS emulator?
1.903 How do I transfer files between AIX and DOS disks?
1.904 Where is the crypt program?
1.905 How do I play audio CDs?
1.906 How can I get the mouse back after unplugging it?
1.907 Where can I get source code to the operating system binary xxxxx?
1.908 What's the difference between the POWER and POWERPC architectures?
1.909 Will there be date rollover problems in the year 2000?
1.910 How can I build an "installp format" file?
2.00 C/C++
2.01 I cannot make alloca work
2.02 How do I compile my BSD programs?
2.03 Isn't the linker different from what I am used to?
2.04 How do I statically link my program?
2.05 How do I make my own shared library?
2.06 Linking my program fails with strange errors. Why?
2.07 Why does it take so long to compile "hello world" with xlc?
2.08 What's with malloc()?
2.09 Why does xlc complain about 'extern char *strcpy()'
2.10 Why do I get 'Parameter list cannot contain fewer ....'
2.11 Why does xlc complain about '(sometype *)somepointer = something'
2.12 Some more common errors
2.13 Can the compiler generate assembler code?
2.14 Curses
2.15 How do I speed up linking?
2.16 What is deadbeef?
2.17 [moved to 2.04]
2.18 How do I make an export list from a library archive?
2.19 imake, makedepend
2.20 How can tell what shared libraries a binary is linked with?
2.21 Can I get a PTF for my C/C++ compiler from the net?
2.22 Why does "install"ing software I got from the net fail?
2.23 What is Linker TOC overflow error 12?
2.24 What is the limit on number of shared memory segments I can attach?
2.25 I deleted libc.a by accident --- how do I recover?
2.26 Where can I find dlopen, dlclose, and dlsym for AIX?
2.27 Where can I find ldd for AIX?
2.28
3.00 Fortran and other compilers
3.01 I have problems mixing Fortran and C code, why?
3.02 How do I statically bind Fortran libraries and dynamically bind
C libraries?
3.03 How do I check if a number is NaN?
3.04 Some info sources on IEEE floating point
3.05 Why does it take so long to compile "hello world" with xlf? (see 2.07).
4.00 GNU and Public Domain software
4.01 How do I find PD software?
4.02 Are there any ftp sites?
4.03 General hints
4.04 GNU Emacs
4.05 gcc/gdb
4.06 GNU Ghostscript
4.07 TeX - Document processing
4.08 Perl - Scripting language
4.09 X-Windows
4.10 Bash - /bin/ksh alternative from FSF
4.11 Elm - Mail reader
4.12 Oberon 2.2
4.13 Kermit - Communications
4.14 Gnu dbm
4.15 tcsh - an alternative shell
4.16 Kyoto Common Lisp
4.17 Tcl/Tk - X-Windows scripting
4.18 Expect
4.19 Public domain software on CD
4.20 Andrew Toolkit
4.21 sudo
4.22 Flexfax/HylaFax and other fax software
4.23 lsof - LiSt Open Files
4.24 popper - POP3 mail daemon
4.26 mpeg link errors version 2.0
4.27 NNTP, INN - news (usenet) news transport protocol, news server software
4.28 Zmodem - File transfer
4.29 Patch - automated file updates
4.30 XNTP - network time protocol, synchronizes clocks
4.31 GNU Screen 3.6.2 and AIX 4.1.x
4.32 PINT -- SCSI scanner software
4.33 Pager/Paging software
4.34 Java Development Kit
5.00 Third party products
5.02 Disk/Tape/SCSI
5.03 Memory
5.04 Others
5.05 C++ compilers
5.06 Memory leak detectors
5.07 PPP
5.08 Graphics adapters.
5.09 Training Courses
5.10 Hardware Vendors
5.11 Debugging aides
6.00 Miscellaneous other stuff
6.01 Can I get support by e-mail?
6.02 List of useful faxes
6.03 IBM's ftp, gopher and WWW presence
6.04 Some RS232 hints
6.05 What publications are available for AIX and RS/6000?
6.06 Some acronyms
6.07 How do I get this by mailserver or ftp?
6.08 Hypertext version of the FAQ
6.09
6.10 comp.unix.aix archive availible on the WWW
8.00 Program listings
8.01 What hardware do I have? What is availible? WITS?
8.02 Cleaning up utmp, who, and accounting problems
8.03 How do I set up postscript accounting?
8.04 How can I find out the machine type?
8.05 Updating to 3.2.5
8.06 How do I do remote backup?
8.06 How do I do remote backup? (cont.)
8.07 How to configure dialup SLIP
8.08 Disabling software flow control; using RTS/CTS.
8.09 How can I hack libc.a to alter how hostnames are resolved?
8.10 How do I make an export list from a library archive?
9.00 Contributors
------------------------------
Subject: 1.000: The AIX operating system - what is it?
This is best answered by reading the text files in /usr/lpp/bos. The
README file there contains general information and the bsd file contain
useful information if you know BSD and/or System V.
The last release for the RT PC is 2.2.1. The latest release for PS/2s
and Intel architecture machines is AIX 1.3; for PS/2s only, 1.2.1. For
the RS/6000, there are three major levels, 3.1, 3.2, 4.1, and various
intermediate levels. IBM has dropped support for 3.1.
For those who don't have a copy of /usr/lpp/bos/README or bsd, I'll
sumarize: IBM tried to follow IEEE, POSIX 1003.1, ANSI C, FIPS and
then X/Open Issue 3. Beyond that, AIX is a combination of System V
and BSD.
------------------------------
Subject: 1.001: I know neither Unix nor AIX
- where do I find more information?
If you are new to Unix, you should look at the other newsgroups in the
comp.unix hierarchy, in particular comp.unix.questions. There are
FAQs more most of these groups as well.
If you need information about C programming, try comp.lang.c or
comp.std.c, the latter for Standard ANSI C issues. comp.lang.c has a
FAQ posting.
------------------------------
Subject: 1.002: What is the Object Database?
From: Uwe Geuder <Uwe.Geuder@informatik.uni-stuttgart.de>
AIX stores most of the system management information in /etc/objrepos,
/usr/lib/objrepos, and /usr/share/lib/objrepos. Files (also referred to
as system object classes) in these directories are adminstered by the
Object Database Manager, ODM, which is a set of library routines and
programs providing basic object oriented database facilities.
Under most circumstances, only SMIT or the commands SMIT call (see
1.100) should be used to change the contents of the system object
classes. A harmless way to look at the object database is to use odmget
<Class> where <Class> is one of the files in /etc/objrepos.
Experienced users can use the ODM editor, odme, to navigate the database
in detail. Modifying the database should only be attempted if you know
exactly what you are doing.
------------------------------
Subject: 1.003: How do I get rid of the verbose error messages?
From: Bjorn P. Brox <brox@corena.n>
Many of the messages from the Unix commands are available in different
languages. This is controlled by the LANG environment variable, the
default being En_US meaning English in the US. All the default messages
have a message number associated with them, e.g.:
$ cat no-such-file
cat: 0652-050 Cannot open no-such-file.
If you prefer the terser Unix-looking error message, set your
environment variable LC_MESSAGES to C, and you will get:
$ cat no-such-file
cat: Cannot open no-such-file.
By default LC_MESSAGES is the same as your environment LANG. Setting
LANG does also work, but should be avoided since it changes
app-defaults lookup etc. See locale(): LC_ALL
------------------------------
Subject: 1.004: Which release of AIX or other products do I have?
New with 3.2.5: The oslevel command shows OS and component levels.
Run oslevel -help to see options
The command 'lslpp -h bos.obj' will show all lines referring to the BOS,
Basic Operating System. E.g.:
Fix Id Release Status Action Date Time User Name
------- --------------- --------- ---------- ---------- -------- ---------
Path: /usr/lib/objrepos
bos.obj
03.02.0000.0000 COMPLETE COMMIT 12/31/69 18:00:00 root
U401864 03.02.0000.0000 COMPLETE COMMIT 11/12/92 20:09:35 root
U401864 03.02.0000.0000 COMPLETE COMMIT 11/12/92 20:09:35 root
U401968 03.02.0000.0000 COMPLETE COMMIT 11/12/92 23:18:21 root
U401969 03.02.0000.0000 COMPLETE COMMIT 11/12/92 23:18:20 root
..........................
U418349 03.02.0000.0000 COMPLETE COMMIT 08/28/93 15:34:13 root
U419950 03.02.0000.0000 COMPLETE COMMIT 08/28/93 15:34:11 root
For AIX 3.2, you may come across discussions on 3.2.0, 3.2.1, 3.2.2,
3.2.3 extended, 3.2.4 and 3.2.5. There is no absolute way to tell which
of these you are running since the newer releases are simply 3.2.0 with
some sets of PTFs added. See above example listing. These selective
fixes could mean there are literally thousands of slightly different
variations of 3.2 in use. Please see section 6 to request some useful
faxes to help with this number game.
AIX 3.2.4 and later attempts to resolve this confusion. The OS is
broken down into subsystems so that updates can be applied to an entire
subsystem. lslpp also sports a new option; use 'lslpp -m bos.obj' to
show what level and update the system is running. You can also use the
new oslevel command. Unless you have a pressing need (such as
applications unsupported on > 3.2.3), it is recommended that you update
to this level. Also see 1.128.
------------------------------
Subject: 1.005: What hardware do I have? What is availible? WITS?
From: C.Deignan@frec.bull.fr (C.DEIGNAN)
[Due to it's length this script has been moved to 8.01]
------------------------------
Subject: 1.006: Is IBM "dropping" AIX?
No. IBM sells and supports AIX 4. However, on January 31, 1997 IBM
will "withraw AIX 3.2.5 from marketing." That is, you won't be able
to purchase AIX 3.2.5 anymore. On December 31, 1997, IBM will
"discontinue Program Services" for AIX 3.2.5. Translation: they will
no longer respond to (most) defect reports for AIX 3.2.5.
The US announcement letter can be read via <http://www1.ibmlink.ibm.com/>.
Pick the US as region, look for "Announcement Letters," then search
for document number 996-245.
------------------------------
Subject: 1.100: I am used to Unix systems programming,
why should I learn SMIT?
Using SMIT is probably very different from your normal way of doing
system administration, but could prove very useful in the long run. In
some areas, in particular TCP/IP, NFS, etc., you can also do things the
normal way, but it is unfortunately difficult to know exactly when the
normal way works. Again, always using SMIT is probably your best way
to go, even when you have to learn a new tool.
What SMIT actually does is build up commands with all required options
to perform the functions requested and execute them. The commands
called and the output they produce are stored in the files smit.script
and smit.log in your home directory. Looking in smit.script may teach
you more about system administration.
------------------------------
Subject: 1.101: How do I turn off the "running man" in smit?
Use smitty, the standard curses version or add this line to your .kshrc file:
alias smit="smit -C"
------------------------------
Subject: 1.102: How do I import an /etc/passwd or /etc/group file
from another box?
If the other box is non-AIX, copy the password and group entries for
the non-system users into AIX's /etc/passwd and /etc/group files.
Then run /bin/pwdck -t ALL. This will create the proper entries in
the shadow password file (/etc/security/users). You should also run
usrck and grpck.
To duplicate the password and group entries from another AIX box,
copy /etc/passwd, /etc/group, /etc/security/passwd, /etc/security/group,
/etc/security/user, /etc/security/limits, /etc/security/environ. The
last three are optional unless you modified them. If you modified
/etc/security/login.cfg, you should also copy that file.
------------------------------
Subject: 1.103: Cleaning up utmp, who, and accounting problems
The best way to fix this problem is to fix the programs which are
causing the behavior in the first place. The short answer is to call
software support and ask for the "UTMPFIX" collection of PTFs.
Virtually all of these problems should be fixed in the 3251 PMP and
the only one I've been able to prove is still broken is using ALT-F4
to close an aixterm.
This applies if you are running an X11R5 xterm on 3.2.
Add this to the top of X11R5 mit/clients/xterm/main.c:
#ifdef AIXV3
#define USE_SYSV_UTMP
#define HAS_UTMP_UT_HOST
#define WTMP_FILENAME "/var/adm/wtmp"
#endif
And your utmp problems should go away. If you want xterminal sessions
to go into the wtmp file you need to define -DWTMP in the Imakefile and
be sure the WTMP_FILENAME is set to the right place.
Section 8.02 contains a small C program that you can use until the
PTFs arrive. The program must be run as root and will periodically
clean up old entries.
Another utmp program was posted to comp.sources.unix, volume 25, issue
96 by David W. Sanderson (dws@cs.wisc.edu) that also works on AIX 3.1.
------------------------------
Subject: 1.104: How to fsck the root filesystem
You can run fsck either in maintenance mode or on mounted filesystems.
Try this:
1. boot from diskette (AIX 3 only)
2. select maintenance mode
3. type /etc/continue hdisk0 exit (replace hdisk0 with boot disk if
not hdisk0)
4. fsck /dev/hd4
------------------------------
------------------------------
Subject: 1.105: How can I unmount /usr to run fsck on it?
From: accapadi@mathew.austin.ibm.com (Matt Accapadi)
[ This is for 3.2. ]
In order to fsck /usr, it has to be unmounted. But /usr cannot be
unmounted because /bin is symbolically linked to /usr/bin. Also
/etc/fsck is symbolically linked to /usr/sbin/fsck.
To work around this, when you boot from the boot/maintenance diskettes
and enter maintenance mode, enter "getrootfs hdisk0 sh" instead of
"getrootfs hdisk0" where hdisk0 is the name of the boot disk. Then run
"fsck /dev/hd2".
------------------------------
Subject: 1.108: How do I see/change parameters like number of
processes per user?
You can use SMIT as described below or simply use lsattr/chdev.
The former will list the current setting as in:
# lsattr -E -l sys0 -a maxuproc
maxuproc 40 Maximum # of processes allowed per user True
and you can then increase the maxuproc parameter:
# chdev -l sys0 -a maxuproc=200
sys0 changed
If you just type 'lsattr -E -l sys0' you will get a list of all
parameters, some of which can be changed but not others.
If you want to use smit, do as follows:
smit
System Environments and Processes
Change / Show Operating System Parameters
- on this screen you can change by overtyping the following fields:
- Maximum number of PROCESSES allowed per user
- Maximum number of pages in block I/O BUFFER CACHE
- Maximum Kbytes of real memory allowed for MBUFS
- toggle fields exist for:
- Automatically REBOOT system after a crash (false/true)
- Continuously maintain DISK I/O history (true/false)
Info 1.30 erroneously suggests that in AIX 3.2.5 you can set different
limits for different users.
------------------------------
Subject: 1.109: How do I shrink the default paging space on hd6?
X-With-Changes-From: Ray Reynolds <reynolds@valisys.com>
1) create a paging space to use temporarily
mkps -s 20 -a rootvg
2) change default paging space hd6 so it is not used at next reboot
chps -a n hd6
3) For AIX 3.1, edit /etc/rc.boot4 and change swapon /dev/hd6;
for AIX 3.2 and 4.x, edit /sbin/rc.boot and change swapon /dev/hd6
swapon /dev/paging00
3a)Since the default system dump device is /dev/hd6 in 4.1.x, it has to
be changed to the temporary swap device before you remove the old
swap device.
sysdumpdev -p /dev/paging00
4) Update information in boot logical volume
bosboot -a (3.1)
bosboot -a -d hdisk0 (3.2 & 4)
5) shutdown and reboot
6) remove current hd6 and create a new one of smaller size
rmps hd6
mklv -y hd6 -t paging rootvg <size of PS in 4 Meg blocks>
7) Re-edit /etc/rc.boot4 (3.1), /sbin/rc.boot (3.2) to swap to /dev/hd6
swapon /dev/hd6
7a)On AIX 4, change the dump device back to hd6:
sysdumpdev -p /dev/hd6
8) Update information in boot logical volume
bosboot -a (3.1)
bosboot -a -d hdisk0 (3.2 & 4.1)
9) change current paging device (paging00) so it is inactive at next boot
chps -a n /dev/paging00
10) shutdown, reboot, remove paging00 using the command:
rmps paging00
You can check your paging space with `lsps -a`
------------------------------
Subject: 1.110: The swapper seems to use enormous amounts
of paging space, why?
When you run ps, you may see a line like:
USER PID %CPU %MEM SZ RSS TT STAT TIME CMD
root 0 0.0% 14% 386528 8688 - S 17:06 swapper
This is normal behavior, the swapper looks to ps like it has the entire
paging space plus real memory allocated.
------------------------------
Subject: 1.111: How much paging space do I need?
See answer 2 in question 1.300.
------------------------------
Subject: 1.112: How do I mount a floppy disk as a filesystem?
From: op@holmes.acc.Virginia.EDU (Olaf Pors)
You can build a filesystem on a floppy and mount it, however the
filesystem will be read only. The reason that the filesystem will be
read only is because AIX Version 3.1.5 cannot create a journal log on a
diskette. The intended use is for temporary access to read only data.
The diskette file system must be unmounted after use and during system
backup procedures or errors could occur.
To make the read only filesystem on a floppy:
1. Make a subdirectory on an existing filesystem and place all of the
files that the diskette will contain into this subdirectory.
2. Enter the following command to create a prototype file containing
information about the new filesystem, in the example /dir_struct
is the pathname of the subdirectory created in step 1, and
proto_filename is the name of the prototype file to be created.
proto /dir_struct > proto_filename
3. Place a formatted floppy into the drive.
4. Edit the prototype file and replace the first line with the following:
<noboot> 0 0
5. Enter the following command to make the filesystem on your floppy:
mkfs -p proto_filename -V jfs /dev/fd0
6. Create the directory upon which you will mount the floppy based
filesystem, or you can use /mnt. Mount the filesystem:
mount -r -V jfs /dev/fd0 /your_mount_point
7. To unmount the filesystem:
umount /dev/fd0
Since the filesystem is read-only it may be of limited use but if you
are going to use it for utility programs and other data that does not
change much, it may still be useful. If you need to change the data,
you can copy the directory from the floppy into another directory, make
your modifications, and remake the filesystem using this procedure.
------------------------------
Subject: 1.113: How do I remove a committed lpp?
AIX 3.2.5: you can get rid of COMMITTED lpps/ptfs by installing with the force
option and then rejecting the package.
AIX 4.1 users: installp has a new option, uninstall (-u) which can be
used to remove lpps.
------------------------------
Subject: 1.114: How can I recover space after installing updates?
From: Milt Cloud <cloud@ux1.cso.uiuc.edu>
Note: If you are a /usr server, do not use this because the files
mentioned below are needed by /usr clients and cannot be deleted.
Installp creates numerous files in /usr to clean up after
failed/rejected installs and also for de-installing uncommitted lpps.
Once you have COMMITted packages you can remove these files safely.
Depending on your installation activity the numbers can be significant:
hundreds-to-thousands of files, megabytes of data.
Files eligible for removal are associated with each "product" you have
installed; the largest collection being due to bos. After
COMMITting bos lpps, you may safely remove all files of the form:
/usr/lpp/bos/deinstl*
/usr/lpp/bos/inst_U4*
/usr/lpp/bosadt/deinstl*
and /usr/lpp/bosadt/inst_U4*
You may repeat this for all additional COMMITted products (e.g.,
bostext1, bosnet, xlc) you have on your system.
This problem of lingering install files is a known defect in installp.
If you have installed PTF U411711 (or any superseder of it: U412397,
U413366, U413425) the deadwood in /usr will not be quite as prevalent.
No single PTF currently available completely corrects this problem.
On my own 320, the following freed up 12.4M in /usr:
# rm -R /usr/lpp/bos/deinstl*
# rm -R /usr/lpp/bos/inst_U4*
------------------------------
Subject: 1.115: Where are the AIX log files kept?
From: dirk@kimosabi.ucsc.edu (Dirk Coldewey)
AIX logs messages as specified in /etc/syslog.conf. Here's an
example
#
*.err;kern.debug;auth.notice;user.none /dev/console
*.err;kern.debug;daemon,auth.notice;mail.crit;user.none /var/adm/messages
lpr.debug /var/adm/lpd-errs
*.alert;kern.err;daemon.err;user.none operator
*.alert;user.none root
*.emerg;user.none *
# for loghost machines, to have authentication messages (su, login, etc.)
# logged to a file, un-comment out the following line and adjust the
# file name as appropriate.
#
# if a non-loghost machine chooses to have such messages
# sent to the loghost machine, un-comment out the following line.
#
auth.notice /var/log/authlog
mail.debug /var/log/syslog
# following line for compatibility with old sendmails. they will send
# messages with no facility code, which will be turned into "user" messages
# by the local syslog daemon. only the "loghost" machine needs the following
# line, to cause these old sendmail log messages to be logged in the
# mail syslog file.
#
user.alert /var/log/syslog
#
# non-loghost machines will use the following lines to cause "user"
# log messages to be logged locally.
#
user.err /dev/console
user.err /var/adm/messages
user.alert `root, operator'
user.emerg *
------------------------------
Subject: 1.116: How can I log information about ftp accesses to a file?
From: elr@trintex.uucp (Ed Ravin)
From: map@hal.maths.monash.edu.au (Michael Page)
1) In /etc/syslog.conf, add the line:
daemon.debug /tmp/daemon.log
2) # touch /tmp/daemon.log
# refresh -s syslogd
3) Modify your inetd.conf so that ftpd is called with the "-l" flag.
You may also want the "-d" flag. This can be done with 'smit inetdconf'.
All the syslog messages from various system daemons should now appear in
the file "/tmp/daemon.log".
------------------------------
Subject: 1.117: How do I find a file name from the inode number?
From: /G=Bill/S=Mansfield/O=P00S38E/OU1=notes/DD.HPNOTES=Bill_Mansfield/mcd/us#a
#
MCD@mhs-mcdusa.attmail.com (Bill Mansfield)
ncheck -i nnnn /mntpoint
------------------------------
Subject: 1.118: How do I set up postscript accounting?
From: taluskie@utpapa.ph.utexas.edu (Vince Taluskie)
Ephraim Vider originally wrote this program to configure postscript page
accounting. It acts as a backend wrapper which logs accounting
information in /etc/qconfig and can be ftp'd from utpapa.ph.utexas.edu
in /pub/aix/psacct.tar.Z.
Compile with:
cc pswrap.c -o pswrap -lqb
and then make this program suid root:
chown root pswrap
chmod u+s pswrap
If this step is not done, the printer will hang.
Then start up SMIT and go to :
Spooler
Manage Local Printer Subsystem
Local Printer Queue Devices
Change / Show Characteristics of a Queue Device
<Select Queue>
<Select Device>
and change "BACKEND PROGRAM pathname" to the full pathname of pswrap
since pswrap will now handle the backend interface with the queue.
A stream of info will be written to a logfile in /tmp (prob lp0.log) but
this file is mainly used for status info and raw pagecounts. If the
accounting data is going to the qconfig-specified acctfile, then use the
'pac' command to read it. I prefer to have readable ascii data files
instead, so I just comment out the '#define WANT_PAC' line and it will
only go to the ACCTFILE specfied in pswrap.c.
[pswrap.c source has been moved to section 8.03]
------------------------------
Subject: 1.119: How do I create boot diskettes?
In AIX 4.1.x and 4.2 you cannot, the kernel and ram drive don't fit on
a diskette. You should get "0301-174 bosboot: Invalid device /dev/fd0
specified!" if you try.
For AIX 3.2.x you will need to have four formatted diskettes.
boot disk: bosboot -d /dev/fd0 -a
display disk: mkdispdskt
display extension disk: mkextdskt
Install/Maintenance disk: mkinstdskt
AIX 3.2.5 may require a fifth boot diskette if you have a FDDI adapter
in the machine. It is the "communications extension" diskette.
------------------------------
Subject: 1.120: Where can I find tools for performance monitoring?
Free X based performance watcher: xsysstats - <ftp://ftp.x.org/contrib/>
For 3.2 a few tools are available in /usr/lpp/bosperf. There are tools
to monitor traces, I/O events, CPU, virtual memory, disk block usage,
kernel extensions, etc. It even has a simulator, rmss, that allows one
to try out different memory size configurations to see how it impacts
performance. See 6.05 for the AIX Performance and Tuning Guide.
The Monitor program is an AIX/6000 System performance monitor program.
Monitor can be used to display system statistics of various short time
performance values. Monitor program is available for anonymous ftp from
<ftp://ftp.funet.fi/pub/unix/AIX/rs6000/monitor-2.1.1.tar.Z> -file.
New to version 2 (released as version 2.1.1)
* Allow logging of information on interval basis in ascii format.
The logfile can be specified as a strftime string and can be
compressed.
* Synchronize sample/interval time on wall clock (from 00:00).
* Sample/interval time is now accurate to around 10 milliseconds
(depending on system load).
* User counts for remote and inactive users, and average inactive time.
* System uptime is printed.
* Highlighted headers
* In logmode, filesystem usage is logged
* support for Symmetric multiprocessing cpuinfo (-smp option
or 's' character command).
* help page in interactive mode 'h' or '?' character commands
------------------------------
Subject: 1.121: How can I tell what virtual printer a print queue is using?
From: yoder@austin.ibm.com (Stuart R. Yoder)
Use the command 'lsvirprt'. Don't use any parameters and it will
run in an interactive mode that will give you a menu of all virtual
printers on the system with the queue and device for each one.
------------------------------
Subject: 1.122: Two srcmstr's are less useful than one?
From: hubert@rs530.ncs.mainz.ibm.com (Bernhard Zeller)
This can happen on systems that have no console, or systems with an
async terminal as the console but not attached or turned off. One of the
symptoms is a second srcmstr got run. But the second srcmstr is worthless
as we can't use the stop/startsrc commands, refresh inetd, qdaemon won't
start, etc.
To resolve this, type:
smit chgtty
and add the keyword 'clocal' in following lines:
STTY attributes for RUN TIME
STTY attributes for LOGIN
------------------------------
Subject: 1.123: How do I set the tty name associated with a physical port?
From: accapadi@mathew.austin.ibm.com (Matt Accapadi)
Let's say you wanted to make a tty on the s1 port and call it rs0000
and a tty on the s2 port and call it rs0001.
You could run:
mkdev -c tty -s rs232 -t tty -l rs0000 -p sa0 -w s1 # creates rs0000
and
mkdev -c tty -s rs232 -t tty -l rs0001 -p sa1 -w s2 # creates rs0001
------------------------------
Subject: 1.124: How do I use mksysb to clone a system?
From: joann@ariadne.SLAC.Stanford.EDU (Jo Ann Malina)
I use the following steps on the master machine to clone an AIX system:
1) Remove the password from root.
2) Remove the NIS line from the end of the /etc/group file (the last
line with the +: )
3) Change most of the level '2' designations in /etc/inittab to level
'3' to prevent them from being started up when the new system is
booted (the minimum ones to change are rc.nfs and rc.tcpip)
4) Boot in service mode and change the name and ip address to a "spare"
set to avoid address collision.
5) Clear /tmp, /usr/tmp and /usr/spool/lpd/stat.
6) Run mkszfile and edit it to be sure /usr is as small as possible;
then mksysb from the command line.
The above changes allow me to boot in normal mode the first time, get in
as root, change the above files back and do the other things necessary
to configure the new system.
Then, of course, I go back and clean up and reboot my master machine.
Note: 1 and 2 lets you log in even if you can't get on the network.
It prevents the login process from trying to reach an NIS server.
Step 2 needed only if you use NIS.
------------------------------
Subject: 1.125: How do I retain timestamps with mksysb?
Originally From: graeme@ccu1.aukuni.ac.nz ( Graeme Moffat)
As of AIX 3.2.5 bosrest preserves timestamps and permissions as does pax.
In AIX 3.2.2 /usr/lpp/bosinst/bosnet (for net installs), and bosrest
(tape), the 'pax' commands all have '-pmop' options. m = "DON'T
retain modification times". So, simply change all the '-pmop' to
'-pop' and remake inst/maint diskettes or mksysb tapes.
------------------------------
Subject: 1.126: How can I find out the machine type?
[Due to it's length this script was moved to section 8.04]
------------------------------
Subject: 1.127: Updating to 3.2.5
From: kraemerf@franvm3.VNET.IBM.COM (Frank Kraemer)
(Ed. The following is useful if you have to update a large number of
systems, large being > 3.)
*** WARNING : Modify the scripts if you need dataless, diskless ***
*** or remote /usr support. ***
1) Receive the PMP3250 tape from your AIX support center the PTF number
is U493250.
2) Create a filesystem with 240 MB of space (60 PP's) and mount it as
/dev/pmp3250 - /pub/pmp3250
3) Insert the tape (blocksize is 512) and install PTF U422467
# installp -BXacgq -d /dev/rmt0 bos.obj 3.2.0.0.U422467
4) Use the following script to load the tape in the new filesystem
# cd /pub/pmp3250
# mktape2disk.sh 0 447 <<-- read 447 files from rmt0
[ The mktape2disk.sh script has been moved to section 8.05 ]
------------------------------
Subject: 1.128: AIX fix strategy
From: leedp@austin.ibm.com (Dennis Lee, PMP Release Manager)
First, a little history...
The maintenance strategy for AIX 3.1 was cumulative updates. Every few
months, we'd put all available fixes in one large package and ship it.
There was no real strategy for providing a single fix. Although we'd
occasionally produce an emergency patch, there was no method for
tracking them; if you got a second one, it might overwrite the first.
So, after a few of these patches, it's hard to track.
In AIX 3.2 we introduced a "selective fix" strategy to support
individual fixes. The package contained information about other fixes
that were required for that fix to work correctly. For example, a Korn
shell fix might require a change in libc.a, which might in turn require
a fix in the kernel. This strategy allowed us to keep track of which
fixes were installed to make sure we didn't overwrite one with another,
and make sure they all worked together. But the initial selective fix
design still had a few problems.
o None of the fixes were cumulative. If you got a fix for Korn shell,
you may not receive all of the fixes for Korn shell. This left the
possibility of rediscovering other problems that were already fixed.
o Since we chose to fix everything possible that was reported as a
problem, instead of deferring them to the next release, the number
of available fixes became quite large.
o The number of additional fixes required by any given fix could also
be quite large. Since the installation program ran once for each
fix, the size and complexity of the fix packages grew, and
installation time lengthens greatly.
While developing the AIX 3.2.4 upgrade, we undertook a large effort to
resolve the selective fix concerns, and dramatically increase the
quality of AIX 3.2. The base operating system and most of the optional
program products were split into subsystems. A subsystem is a group of
logically related files. The division was made such that changes to a
given subsystem were less likely to affect other subsystems. In total
there are approximately 500 subsystems, but in practice, files have been
modified in only about half of them. The advantages of the new
packaging strategy are:
o Each subsystem package is cumulative, containing all of the fixes
and enhancements to date for that subsystem.
o The cumulative subsystem package is tested as an entity.
o The number of fix packages is greatly reduced because the number of
subsystems is far fewer than the number of fixes and enhancements.
o The number of other fixes required by any given fix is also greatly
reduced because a subsystem package has requisites only on other
subsystem packages.
o The reduced number of fix packages greatly reduced installation time.
Some customers also told us that they liked the maintenance level
strategy that we used in AIX 3.1. They liked being able to install all
of the known fixes, and they liked knowing what "level" of AIX they had.
To meet these requirements, we produced a Preventive Maintenance Package
(PMP). The PMP is simply a collection of the latest cumulative
subsystem packages tied together in such a way that it can be installed
by selecting a single fix. We also added flags to the lslpp command and
added a new command, oslevel, to show which PMP is installed. Now we
had both! The good attributes of selective fix along with the good
attributes of maintenance levels.
A few Q&As:
Q. Why is the fix I just received 130 megabytes!@#? I already have the
AIX 3.2.4 update installed!
A. Your fix may be part of the AIX 3.2.5 update. AIX 3.2.5 is another
PMP that contains all of the fixes to date, as well as enhancements
to support the PowerPC model 250, and the new high-end RS/2 models
590 and 990, as well as support for new disk and tape drives, graphics
adapters and more.
Q. Why can't you just build my fix on 3.2.4?
A. There really isn't such a thing as 3.2.1 or 3.2.2 or even 3.2.4.
They're just collections of fixes and enhancements built on a 3.2 base.
If the fix for your problem was built prior to 3.2.5, you can get the
older version. But if your fix was built for the first time in a 3.2.5
subsystem, that's the only version of the fix that exists.
See also 6.02.
------------------------------
Subject: 1.129: Are passwords limited to 8 char?
AIX passwords are only significant to 8 characters. You can set a
passwd to more than 8 characters but anything over eight are ignored.
No messages or warnings are given.
Be careful if you're running NIS. You probably want to limit passwords
to 8 char on all machines (6000 and others) to be compatible.
Someone mentioned that DCE supports kerberos which supports passwords
greater than 8 characters.
------------------------------
Subject: 1.130: How do I increase the number of ptys > 64?
From: mick@oahu.cern.ch (Mickey Coggins)
SMIT only allows 64. Try this:
odmget -q"attribute=num and uniquetype=pty/pty/pty" PdAt |
sed "s/0-64/0-512/" |
odmchange -q"attribute=num and uniquetype=pty/pty/pty" -o PdAt
chdev -l pty0 -anum=256 -P
reboot
------------------------------
Subject: 1.131: CERT advisories on sendmail and xterm
The following fixes are available for some CERT advisories on problems
with sendmail and xterm.
sendmail - fix available as U426396
xterm for X11R4 - fix available as U422575
xterm for X11R5 - fix available as U425811
------------------------------
Subject: 1.132: How do I remove a non-existant physical volume?
Thanks to Johnny Shieh (shieh@austin.ibm.com)
To delete a phantom disk from the ODM use reducevg with the pvid
instead of the disk name. You are running some command such as lsvg
or varyonvg and it is griping about a disk that is no longer findable
right? In that warning message, it should give you a pvid. Try one
of the following, (note: reducevg updates the VGDA but not the ODM).
reducevg -f <vgname> <pvid>
ldeletepv -g VGid -p PVid
-g Required, specify the VGid of the volume group you are
removing the physical volume from
-p Required, specify the PVid of the PV to be removed
------------------------------
Subject: 1.133 How do I kill a process that ignores
kill -QUIT -KILL -STOP
If there is i/o pending in a device driver, and the driver does not
catch the signal, you can't kill it - a reboot is the only way to
clear it.
Furthermore, if the process stays hung for more than a few minutes,
you can find out what device is wedged by doing this --
% echo trace -k $(expr <pid> / 256) | crash | tee stack
If you can't figure out what is wrong, print that trace out and call
1-800-237-5511 and tell them that something is broken. Tell them you
want to fax in the nice stack trace that you have as your testcase.
------------------------------
Subject: 1.134: How can I see "console" messages?
From: crow@tivoli.com (David L. Crow)
Use the swcons command to redirect the console to a file. Or use
chcons to do it permanently.
------------------------------
Subject: 1.135: Where can I find TOP for AIX?
TOP functionality is included in an AIX package called Monitor. See
question 1.120 for more information.
------------------------------
Subject: 1.136: How can I restrict root logins to specific terminals?
From: jfh@austin.ibm.com (Julianne F. Haugh)
Read FAX 2737 availible from the 800-IBM-4FAX number discussed in
section 6.02. Refer to APAR IX45701 for fixes related to the rsh style
commands.
------------------------------
Subject: 1.137: How do I merge my /etc/password and
/etc/security/password for Crack?
/usr/sbin/mrgpwd. You must have permissions to read /etc/security/password.
------------------------------
1.138: I lost the root password, what should I do?
From: dramm@csusm.edu (Donald E. Ramm)
Boot from boot diskettes, bootable tape, or bootable CD.
At the Installation/Maint menu select item 4, "Start a limited function
maintenance shell.
At the subsequent "#" prompt enter the command:
getrootfs hdiskN
(where "N" is replaced by the number of a disk on your system
that is in rootvg.)
That will run for about a minute or so and you get a # prompt back. At this
point you are logged in as root in single user mode.
Change to /etc/security and edit the passwd file. Delete the three lines
under root: password, update time (or whatever it's called), and
flags. Save the file.
Then at the prompt, give root a new password.
Shutdown/reboot in normal mode. Log in with new password.
------------------------------
Subject: 1.139: How can I resolve DEV_WAIT status for a local print queue?
From: chuah@sam.po.my (Chuah Teik Chye)
Try "qadm -k && qadm -U"
------------------------------
Subject: 1.140: SMIT problems forcing/overwriting install?
Installp does not support overwriting and installing prerequisite
software at the same time.
------------------------------
Subject: 1.141: Which distribution tape do I have?
From: fuzzy@obelix.ncs.mainz.ibm.com (Thomas Braunbeck)
AIX 3.2.5 (3250-04-09)
| | | |
| | | |
| | | Revision level
| | Enhancement level
| Preventive Maintenance Package (PMP) level
AIX Version, Release, Modification level
------------------------------
Subject: 1.142: How can I get PTF (fixes) via ftp? What is fixdist?
Get a copy of IBM's fixdist package. This X-windows (and curses) program
can help you find and transfer PTFs from IBM to your machine. It is availible
from <ftp://aix.boulder.ibm.com/aix/tools/fixdist/> and further instructions
are displayed after you login. It is worth noting here that the files
fixdist retrieves are often quite large and therefore not recommended
for those with slow connections.
Ciaran Deignan <C.Deignan@frec.bull.com> says that Bull offers AIX
PTFs at <http://www-opensup.bull.com/>. Currently you need to know
exactly what PTF you want, but searching facilities are in beta test
and will be available "real soon now."
------------------------------
Subject: 1.143: Is there an easy way to determine if AIX
has a PTF applied or not?
lslpp -Bl Uxxxxxxx
Where Uxxxxxxx is the PTF id.
------------------------------
Subject: 1.144: How do I recreate a deleted /dev/null?
From: tvweaver@austin.ibm.com (Tom Weaver)
/bin/mknod /dev/null c 2 2
------------------------------
Subject: 1.145: What is a checkstop error?
From: tvweaver@austin.ibm.com (Tom Weaver)
While this may not be the official definition, what it means is that the
hardware has detected a condition that it cannot resolve, and which prevents
normal operation. So, it stops executing instructions, responding to
interrupts, etc. Usually it means that some component of the hardware is
broken.
------------------------------
Subject: 1.146: How do I recover deleted files?
Preferably from a backup. If you don't have a backup, at least one
company, Compunix, claims to have a product that will recover deleted
files. More information is available at
<http://www.catalog.com/compunix/>.
------------------------------
Subject: 1.147: What questions are on the AIX Certified
User/SystemAministrator/etc., exam?
If you want more information, look at
<http://www.rs6000.ibm.com/support/aixcert/>.
There's also a self assessment exam available at
<http://www.rs6000.ibm.com/cgi-bin/TC2/tc2_reg.cgi>. The questions
are supposedly *derived from the same sources* as the AIX
Certification exams. I assume that this means the actual exams cover
much of the same information.
I assume that the actual questions (and especially the answers) are
protected by copyright and possibly other laws, so disclosing them
without IBM's permission would not be wise or legal.
------------------------------
Subject: 1.200: Some info about tape backups
From: Craig Anderson
The following supplements the information on rmt devices in
InfoExplorer. It is based on my own personal experience with IBM tape
drives running on AIX 3.1. No warranty is expressed or implied.
CONFIGURING THROUGH SMIT:
BLOCK size (0=variable length) (ALL)
Sets the tape block size. When reading, the block size must be
set to the block size set when the tape was written. When
using some commands, tapes written with ANY block size can be
read if the block size is set to 0 (variable length) (see
"BLOCK SIZES" below).
Use DEVICE BUFFERS during writes (ALL)
Set to yes, the device will buffer data internally on writes.
This greatly improves performance, but under certain cases may
be undesirable since the data is not written to tape before
returning a good indication.
Use EXTENDED file marks (8mm only)
Extended file marks take up much more space than short (or
non-extended) file marks. But extended file marks can be
overwritten, allowing data not at the beginning of tape to be
overwritten (see "FILE MARKS" below).
RETENSION on tape change or reset (1/4" only)
If set to "no" then the tape will not be retentioned
automatically when the tape is inserted. Note that this will
take effect only after the device is used.
FILE MARKS:
Tape devices support multiple tape files. Tape files are the
result of a backup/cpio/tar/dd type command, where the device is
opened, written to, and closed. Because tapes allow large
quantities of data to be written on a single tape, several backups
(that is, tape files), may be combined on one physical tape.
Between each tape file is a "tape file mark" or simply "file
mark". These file marks are used by the device driver to indicate
where one tape file ends and another begins.
B E
<------- O O ------->
T T
__ ____________________________ _______________
physical | \ | | \ |physical
beginning| \ | tape | \ | end
of | \ | file | \ | of
tape | \ | mark | \ | tape
|_____\________|_______|__________\_________|
Note that there is a distinction between the beginning of tape
(BOT) side of a file mark and the end of tape (EOT) side of a file
mark. If the head is on the BOT side of a file- mark, "tctl fsf
1" command will move only to the EOT side of the same file mark.
With the 1/4" tape drive, writing can only take place
sequentially, or after blank tape has been detected. You cannot
write over data on the tape (except at BOT). If you wish to add
data to a tape which has been written and then rewound you should
space forward file mark until an error occurs. Only then can
you start writing again.
With an 8mm tape drive, writing can only take place before blank
tape, an EXTENDED file mark, or at BOT. Thus if several backups
have been made on one tape and you wish to overwrite one of the
backups, position the tape to the place you wish to start writing
and issue the following commands:
tctl bsf 1
tctl eof 1
The first command skips back to the BOT side of the same file
mark. The second command rewrites the file mark (writing is
allowed before extended file marks). The erase head will erase
data ahead of the write head, so that after writing the file mark
the head will be positioned before blank tape. Only after this
may you start writing over data in the middle of the tape. (All
data beyond where you are currently writing will be lost). Note
that you cannot write over short file marks. In order for this to
work, the tape must have been written with extended file marks
(use smit to change this).
With the 9-track drive writing can take place anywhere on the
tape although overwriting single blocks of data is not supported.
On the 8mm drive extended filemarks use 2.2 megabytes of tape and
can take up to 8.5 seconds to write. Short filemarks use 184K
and take up to 1.5 seconds to write.
BLOCK SIZES:
When data is written to tape it is written in blocks. The blocks
on a tape are separated by inter-record gaps. It is important to
understand the structure of the written tape in order to
understand the problems which can occur with changing block
sizes.
In fixed block size mode all blocks on the tape are the same
size. They are the size of the block size set in the device
configuration. All read()s and write()s to the tape drive must be
a multiple of the fixed block size.
In fixed block mode a read() will return as many blocks as needed
to satisfy the read() request. If a file mark is encountered
while reading the tape only the data up until the file mark will
be returned.
It is not possible for the tape drive to read a tape whose block
size is not the same as the block size in the device
configuration. (Unless the device configuration is in variable
size blocks.)
In variable block size (0) mode, the blocks written on the tape
are the size of the read() and write() requests to the device
driver. In this case, the actual block sizes on the tape can be
changed using the options to the backup commands (tar -C, cpio -C,
backup -C).
In variable mode, read() requests greater than size of the block
on the tape will return only the data from the next block on the
tape. It is this feature that allows tapes written in any block
size (fixed or variable) to read with the dd command (the output
from the dd command may be piped to restore, tar, or cpio for
example.) Note that backup, tar, and cpio cannot read all tapes
by using a large block size because they assume there is an error
if they get a short read().
dd ibs=128k obs=16k if=/dev/rmt0 | ...
The tape head is always positioned at an inter-record gap, file
mark, or blank tape after reading or writing.
With the 8mm tape drive, using a fixed block size which is not a
multiple of 1K is inefficient. The 8mm tape drive always writes
internally in 1K blocks. It simulates the effect of variable
block sizes, but, for example, using a fixed block size of 512
bytes (or using variable block size and write()ing 512 bytes at a
time) wastes one half of the tape capacity and gives only one half
the maximum transfer rate.
To figure out a tape's actual block size try:
1). Set the tape to variable block size.
2). "dd if=<tape> of=/tmp/dummy bs=128k count=1"
3). "ls -l /tmp/dummy"
4). The number of bytes in "/tmp/dummy" is the physical block size.
EXCHANGING DATA WITH NON-UNIX AND OTHER VENDORS MACHINES:
Many tape drives support both variable and fixed block sizes.
Variable block mode writes block sizes the size of the write
command issued (tar and backup specify this with the -b option).
In fixed mode, block sizes are fixed and all writes must be a
multiple of the fixed block size.
Unix often internally chops larger reads and writes up into
manageable pieces (often 65535, 65534, or 65532 bytes) before
doing the actual reads and writes. This means reads and writes of
64K bytes are often broken up into a 65535 byte record and a 1
byte record (In fixed mode the write will fail). Block sizes >=
64K (-C128 and greater) should be avoided for this reason. AIX
does not break up read and write requests, but be aware of the
situation on other machines.
If the tape is written in an unknown block size then set the
device configuration in smit to use variable size blocks, use the
"dd" command with a large input block size, and pipe it to the
restore command. For example:
chdev -l rmt0 -a block_size=0
dd if=/dev/rmt0 ibs=128k obs=16k | tar -tvf-
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