Edit: A blast from the past. I wonder how many customers still run AIX 6.1?
Originally posted December 11, 2007 on AIXchange
The IBM AIX Version 6.1 Differences Guide has been released, and I suggest you take the time to read it. I’ll run down some highlights, chapter by chapter.
Chapter 2–Information here includes things like turning off jfs2 logging to increase performance (page 34), taking a jfs2 internal filesystem snapshot (page 34-35) and turning on encrypted filesystems (page 38).
Chapter 3–The focus is workload partitions. Also discussed are updates and changes that have resulted in different performance tools to account for workload partitions. On page 158 it’s noted that the default size of the argument area on the command line has been changed. In older versions of AIX, if you tried to do a rm * in a directory with too many files, you’d get an error. You could either manually find smaller lists of files to give to the rm command, or run a find with xargs and do your rm that way.
Page 161 illustrates how you can limit the number of threads per process and the number of processes per user. Included is an example of a developer writing code that would bog down the whole machine. But now you can keep developers from bringing your machine to its knees.
You will see new entries when you run ulimit –a:
time(seconds) unlimited
file(blocks) 2097151
data(kbytes) 131072
stack(kbytes) 32768
memory(kbytes) 32768
coredump(blocks) 2097151
nofiles(descriptors) 2000
threads(per process) unlimited
processes(per user) unlimited
Page 169 cites the IBM Systems Director Console for AIX, a default feature of AIX 6.1. If you go to https://localhost:5336/ibm/console, you should get a login screen. Then login with the root password, then log on and see what it has to offer.
Page 178 contains info on the Distributed Command Execution Manager (DCEM), which allows you to run the same command on multiple machines. When I was at IBM, I used a similar tool that saved me the hassle of logging into 100 different machines. I just logged into the master server and issued the command, and it would run on all of the machines and return the result to my master machine. As I said, DCEM seems very similar to this concept.
Page 202 talks about restricted tunables. IBM is suggesting that system administrators shouldn’t modify these tunables unless instructed to do so by support. Because they’re not supposed to be modified, they’re not displayed unless you use the -F flag. You’ll also get a warning message if you change one of the restricted tunables. This action will also cause a notification to go to the error log.
Page 215 goes into detail about the performance settings that come with AIX 6.1 out of the box. This is a change from the old behavior–you no longer must go in right away and tune minperm and maxperm and enable aio servers for database machines. These settings are all now set up correctly by default. On Page 217 it states that AIX 6 will enable I/O pacing on new installs.
I also recommend that you read about all of the new security enhancements. These are found in Chapter 8 starting on page 253. Look for things like weak root passwords and how to install your machine secure by default. I know the first thing we’ve always done after a fresh install is to go in and disable the unneeded services from /etc/inetd.conf, /etc/inittab, etc. Now the OS is installed with minimal services, allowing you to activate only the additional features that you actually need.
There’s plenty more, but hopefully this has convinced you to download the guide yourself. Much is improved with AIX 6.