MEM stays high on AIX

[mgauteng]

Hello tek tips
I have a p5 series server aix 5L with database re db2 running but after db is shutdown memory still remains high.Does aix have a way of releasing physical memory back to the system are there setting i need to change

 

[mrn]

As well as nmon & topas (I'd use both) the following come in handy

CPU Monitoring - netpmon 
Memory Montiroing  - svmon, netpmon, and filemon 
I/O Subsystem - filemon, fileplace 
Network -  netpmon, tcpdump 
Processes & Threads - svmon, truss,kdb, dbx, gprof, fuser, prof

Mike

"Whenever I dwell for any length of time on my own shortcomings, they gradually begin to seem mild, harmless, rather engaging little things, not at all like the staring defects in other people's characters."

 

[mrn]

&

CPU Monitoring  - vmstat, iostat, topas, sar, time/timex 
Memory Montiroing -  vmstat, topas, ps, lsps, ipcs 
I/O Subsystem - vmstat, topas, iostat, lvmstat, lsps, lsatt/lsdev, lspv/lsvg/lslv 
Network -  netstat, topas, atmstat, entstat, tokstat, fddistat, nfsstat, ifconfig 
Processes & Threads -  ps, pstat, topas

Mike

"Whenever I dwell for any length of time on my own shortcomings, they gradually begin to seem mild, harmless, rather engaging little things, not at all like the staring defects in other people's characters."

 

[misstc]

Hi

If you choose to change the lru_file_repage and minperm settings you may also need to look at memory affinity if this is running on a partition rather than in full system mode. When you carry out dlpar activities or reboots you may end up with different amounts and sizes of memory pools. By default the vmm settings are applied to each individual memory pool, so you could still end up with a lot of paging space activity if you have more than one memory pool.

There are some tech notes which suggest the memory affinity setting isn't applicable on AIX5.3, however we have just run into this issue and IBM told us to look at setting this.

 

[mrn]

Just read a very interesting artical from IBM System mag open systems version Aug/Sept 2006 which states IBM are now recommending the following

The new recommendations are to leave maxclient and maxperm at their default settings of 80, but to still set minperm to something like 5. We also don't change the strict settings. Instead, we alter other parameters as follows:

vmo -p -o minperm%=5
vmo -p -o lru_file_repage=0
vmo -p -o lru_poll_interval=10

Have a read at

http://www.ibmsystemsmag.com/ME2/di...91&tier=4&id=6E6FC39B462A4367A6BC76F434CBE3CF

Mike

"Whenever I dwell for any length of time on my own shortcomings, they gradually begin to seem mild, harmless, rather engaging little things, not at all like the staring defects in other people's characters."

 

[RodKnowlton]

Good article, Mike.

I still think the idea of "recommended settings" with no actual machine load context is pointless, but there's some good information in there regarding the purpose of some settings.

Also worth noting: those are the author's recommendations, not IBM's.

IBM's recommended settings for the great mass of systems, by definition, would be the defaults. Why else have them as defaults?

Of course this, IBM is also the company that produced an excellent PC operating system (OS/2) and a line of PCs (Aptiva) that couldn't run it, at the same time.

- Rod




IBM Certified Advanced Technical Expert pSeries and AIX 5L
CompTIA Linux+
CompTIA Security+

Wish you could view posts with a fixed font? Got Firefox & Greasemonkey? Give yourself the option.

 

[dawaves]

I would try mounting your DB filesystems under Concurrent I/O or CIO. DB's should'nt use the OS's file buffer cache to read/write data, but instead see the disk drives as raw logical volumes. When you mount your filesystems w/ CIO, there is no need to tune since the DB application goes directly to disk.

Also adding memory may help but I don't see any paging going on in your system.

 

[kHz]

You don't want your DB binaries mounted on CIO, though. And CIO is only available for Enhanced JFS, but if you are using JFS then you should use DIO.

There are articles from IBM and Oracle that document setting minperm%=5. Of course, with any system you should monitor and tune as necessary.