Systems Management for AIX
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Covered here and see the below sections:
- System Management Information and documentation
- Shell Scripts
- Start up and shut down
- Disks and LVM
- File systems
- Paging space
- Backup and restores
- High Availability
- Security
- Network
- Network File System (NFS)
- User Accounts
- Printing
- Terminals and Modems
- Accounting
- IBM HTTP (Apache)
- NIS
- DNS
- Sendmail and e-mail
- Open Source additions
- Clusters
- Misc
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Topics already covered in this Wiki site else where are:
1 System Management Information and documentation
2 Shell Scripts
AIX offers the following shells:
| Shell |
Binary |
Name |
| ksh |
/usr/bin/ksh |
Korn Shell 88 |
default |
| ksh93 |
/usr/bin/ksh93 |
Korn Shell 93 |
| bsh |
/usr/bin/bsh |
Borne Shell |
| csh |
/usr/bin/csh |
C Shell |
3 Start up and shut down
Start up
Push the power cables in and if necessary press the white button or use the HMC to start the machine.
Shut down
There are many ways of shutting down AIX.
By far the most recommended way is to log on as root and use the shutdown command - this performs an orderly shutdown and warns users and processes before proceeding to flush the disks and close services down. Use the following options:
| Command |
Comment |
| shutdown |
orderly stopping of AIX but first warn UNIX users for a few minutes (only users with a shell which can be rare these days) |
| shutdown -F |
Quickly stop AIX - no warnings to users |
| shutdown -Fr |
Quickly stop AIX and restart it |
| shutdown -Fh |
Quickly stop AIX and halt the processors |
Other methods will work but some high risk command may result in file system corruption that will be corrected on reboot.
If it is an extreme case and need to stop more quickly:
| Command |
Comment |
| halt |
flush the disks and stops the processor |
| halt -q |
stops the processor - ONLY DO THIS IS YOU FEEL LUCKY |
4 Disks and LVM
Logical Volume Manager = LVM is part of AIX, so no extra costs, not optional you have to use the LVM and actually very good.
It manages disks and their attributes
- commands and integrated in to smit, smitty and webSM
- database of configuration information
- supported by the device drivers
- adds higher level functions and features like mirroring, RAID, allocation
If you want a quick Class 101 or reminder on take the following link: A Lecture on LVM
AVOIDING Disk Crashes
- Rule One: don't let this stop your system
- RAID5 or mirror everything including paging space
- Rule Two: Monitor error logs
- Make sure you know when a disk failed and fixed before the next problem hits
- Rule Three: Call hardware support
- That is what they are for and you are paying for
- Rule Four: Don't meddle
- Only try, if you really know what you are doing
- Rule Five: Read and practice
- Get the AIX Redbooks and try it safely on a non-production machine before using it in an emergency
5 File systems
AIX supports various filesystems
| Name |
Full Name |
Cost |
Description |
| JFS |
Journal File System |
This comes with AIX at no additional charge. |
This is the original filesystem for AIX and been in use for 15+ years. This comes with AIX at no additional charge. While it is very much supported it is largely functionally stable i.e. most development and increases in sizes and function are now going into JFS2.Z |
| JFS2 |
second generation file system |
This comes with AIX at no additional charge. |
and now the default on most new AIX 5L system. The prime difference is the extend based space management. This means that space is dynamically allocated on demand. It also handles much bigger file systems. |
| NFS |
Network File System |
This comes with AIX at no additional charge. |
This is the standard NFS found on most UNIX system. AIX 5L supports versions 2, 3 and 4. |
| VeritasFS |
Veritas File System |
Ask Veritas Sales |
This is a third party add-on to AIX. Many computer rooms have standardized on Veritas FS on other UNIX operating systems like Solaris and HP/UX. And so use VeritasFS on AIX for consistence. The JFS2 offers similar but not the same functions. Many people use JFS2 (the costs). For more information go to http://www.veritas.com/us/products/filesystem/ |
| GPFS |
IBM General Parallel File System |
Ask IBM Sales |
GPFS is a network filesystem for a consistent and reliable filesystem across many machines. Many of its features are not available elsewhere. For more information go to http://www.ibm.com/servers/eserver/clusters/software/gpfs.html there is also a good Redbook at http://publib-b.boulder.ibm.com/Redbooks.nsf/RedbookAbstracts/sg245165.html?Open and a Primer at http://www.ibm.com/servers/eserver/pseries/software/whitepapers/gpfs_primer.html and GPFS for AIX documentation at http://publib.boulder.ibm.com/clresctr/windows/public/gpfsbooks.html |
What is the performance difference between non-network file systems: JFS, JFS2 and VeritasFS?
The answer is not a lot. The filesystem layer is thin when compared to other services and the performance of disks, so the differences are very small and in many cases so small they can be hard to measure.
If you want a quick Class 101 or reminder on take the following link: A Lecture on JFS
6 Paging space
One of the original UNIX manuals (we are talking 20 years ago here) stated that if you run out of paging space then "Absolute mayhem is guaranteed". The UNIX kernel has no choice but to take seemingly random processes and kills them and process creation will fail. In actual fact it will crash processes that are requesting more virtual memory.
How much virtual memory = paging space do you need?
The answer is "enough".
See the below Class 101 for more information and suggestions.
If you want a quick Class 101 or reminder on take the following link: A Lecture on Paging Space
7 Backup and restores
AIX includes the following regular UNIX backup commands:
- pax
- tar
- cpio
- backup and restore
There is also the special AIX command for making a backup of the AIX disks to tape
- mksysb
This mksysb command can be used to recover on to a replacement machine or clone a machine to save set up time. It can also be used to save the data to a disk file that can be used with IBM Network Installation Manager (NIM) which is part of AIX at no extra cost - to network install for recovery or cloning. This can even be done on to machines that have different configurations.
Many large sites user remote centralized backup systems like the following:
8 High Availability
While there are options for High Availability the IBM HACMP is by far the most popular AIX solution.
This is covered in its own section at the following link High Availability
9 Security
The security benefits of AIX 5L include:
- Enhanced system security
- Enhanced network security
- Effective system management assistance
- A repertoire of useful applications and tools
- Tight access control
- Robust encryption capabilities
For more information go to the AIX Security Guide at http://www-03.ibm.com/servers/aix/overview/security.html
10 Network
Networks are like plumbing:
- if it works - it is boring
- if it has problems - it is a nightmare
- if the pipes are not large enough, it can make the service (server) look really bad
Clearly, networking is important for all servers. Take a look at Basic Setup post installation - things to do after the installation for more information as getting your machine on the network is one of the first tasks.
To change network options use : no
To list the current settings : no -a
Sets a new value until reboot : no -o xyz=value
Sets a new value active after reboot : no -r -o xyz=value (only available in 5.2 and higher)
Sets a new value now and after reboot: no -p -o xyz=value (only available in 5.2 and higher)
11 Network File System (NFS)
AIX has NFS versions 2, 3 and 4 and this is a pretty standard feature of UNIX.
Most systems administrators use smitty to set up exported filesystems or directories.
Use: smitty nfs
The exported details are held in /etc/exports
You can add permanent imported filesystems via smitty (as above) or just use the mount command directly.
For example: mount blue:/home /mnt
This assumes the mount point is already expected for anyone or this particular machine.
AIX can mount for read/write, read-only or read/mostly.
You will find NFS reading is quite efficient but NFS writing is slower - this is a feature of the NFS protocol rather than AIX - but its worth knowing if you just want to share a large amount of files.
NFS stats are found using the nfsstat command.
For monitoring NFS stats use topas for the totals NFS calls or nmon.
12 User Accounts
AIX has the usually UNIX Users and Groups. To create and manage these use smitty
- For groups use: smit group
- For just a few users use: smit user
- Set password: passwd
New users have to change it on first login - if you don't like this or the first attempt will be FTP (can't change the password with FTP) you can su to the user (twice if you are root) or edit /etc/security/passwd.
For high numbers of users use the command: mkuser
Use smit to work out the options, that you need.
AIX has
- password aging
- password restrictions
- can add extra (secondary) password checking applications like challenge response systems
/etc/passwd does not have passwords in it to stop possible hacking attempts on encrypted passwords. They are stored in /etc/security/passwd.
Only root access for increases security - unless you use NIS. passwd, mkuser and chuser update the files in /etc/security/passwd which are stanza based files ie.e paragraphs in this format
name:
parameter = value
parameter = value
It includes flags like ADMCHG, meaning the system admin changed the password so the user has to change the password on first login. The /etc/security/group files format is similar.
When creating users the /usr/lib/security/mkuser.default determines the defaults and you can change this to your standards.
A further file /etc/security/user contains full details of the user accounts like: time out value, logon retries and more.
The file /etc/security/limits contains the ulimit advanced numbers like: fsize, core, cpu, data, rss, stack, nofiles
Check the comments at the top of the file for example: -1 means no limit. You can set limits per user. If not set the defaults apply.
Useful commands to find your users:
- who
- last details login events and shutdowns
- last root console
- last | grep shutdown
13 Printing
14 Terminals and Modems
There is a famous saying with woodwork "measure twice and cut once". The same can be said of these serial/RS232 devices - "check the cables twice and the software once".
There is less people using these devices every year due to cheap and fast networks.
the only exception is the dumb console used to install AIX in the first place and that only applies to old machines as the vast bulk of new machines are connected to a HMC as the console device.
Smitty can be used to set them up.
Three ways of attaching terminals or modems
- RS232 serial ports
- 2 ports on older systems
- 4 ports on some newer systems
- Terminal concentrator
- Adapter and expansion box with RS232 ports
- 8 to 128 way
- Network Terminal Server
- telnet sessions from RS232 terminals but AIX does not see this as a terminal but a telnet connection
- Modems still use the RS232 ports
Use "smit tty" to make the port available (S1, S2 are the motherboard serial ports or port number)
- Assign the right terminal type - saves users doing this
- Set getty start = true
- Set terminal characteristics 8 bits, no parity, 9600 BAUD, etc.
- many people use 19200 as standard.
15 Accounting
Not a lot of people using UNIX accounting due to the performance overhead. With AIX 5.3 we now have Advanced Accounting this is completely different an so good that it can be used for Performance Monitoring of different workloads.
Volunteers needed.
Here is the reference material that is a good starting point:
| Document |
URL |
| Accounting and Auditing on AIX 5L Redbook |
http://www.redbooks.ibm.com/abstracts/sg246396.html |
| Advanced Accounting Utilities for AIX |
http://www.alphaworks.ibm.com/tech/aaautilities |
| Advanced Accounting Whitepaper |
http://www-1.ibm.com/servers/aix/whitepapers/aix_accounting.pdf |
16 IBM HTTP (Apache)
IBM supports a modified version of the Apache "httpd" web server. The additions are for performance.
It is not installed in the regular Apache default directory, which is probably a good thing.
Apart from that it works just like the original.
IBM HTTP Server features include:
- Easy installation
- Support for SSL secure connections
- Fast Response Cache Accelerator
- IBM support as part of the WebSphere bundle
- Administration Server that helps to administer and configure IHS servers.
- Help information that uses the easy-to-navigate design that is common to all WebSphere products
- IBM HTTP Server also runs on HP-UX, Linux, Solaris, Windows 2000 and Windows NT
17 NIS
Systems Administrators seem to love or hate this depending on whether of not they are using it every day.
18 DNS
AIX supported the named daemon for DNS. DNS is a large subject.
My favorite book in the subject is "DNS and Bind" from the O'Reilly publisher.
19 Sendmail and e-mail
AIX supports Sendmail - has anyone some hints and tips?
There is a chapter in the pSeries AIX System Administration Redbook - see the top of this page for where to get this online.
20 Open Source additions
AIX has a large range of Open Source tools, applications etc already ported and packaged ready for you to install
21 Clusters
IBM's solution to clusters includes GRID (not covered here but fully available on AIX and Cluster System Management (CSM)
CSM is designed minimize the cost and complexity of administering clustered and partitioned systems by enabling comprehensive management and monitoring of the entire environment from a single point of control. In addition to providing all the key functions for administration and maintenance of distributed systems, CSM is designed to deliver the parallel execution required to manage clustered computing environments effectively. CSM supports homogeneous or mixed environments of IBM servers running AIX 5L or Linux.
More information, documentation and FAQ can be found at http://www-03.ibm.com/servers/eserver/clusters/software/csm.html
22 Miscellaneous
cron
Every UNIX flavour has cron but it seems they are in different places ...
- crontabs files can be found in /var/spool/cron/crontabs/<user>
- Log files can be found in /var/adm/cron/log
- The allow/deny files can be found in /var/adm/cron/cron.allow and /var/adm/cron/cron.deny
Edit cron files with crontab -e
AIX has skulker for cleaning up tmp files that can also clean up other places - check the documentation.
Log files
There are special system Log files (these are circular log file)
List System log names: alog -L
Examples: boot bosinst nim console
List File: alog -o -t boot
You can also check the system error log with the errpt command:
- Summary: errpt | pg
- Full details: errpt -a | pg
- Empty the error log: errclear 0
What version os AIX am I running including maintenance level (ML) ?
Use:
- oslevel -r
- instfix -i | grep ML
How can I see microcode and firmware levels of the system, adapters and devices ?
- lsmcode -A (Displays microcode level information for all supported devices)
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