tuning sytem

[velasco]

Hi, i have a HP 9000/809/K100 with a HPUX 10.20 , 120 Mo RAM and I have 64 MO for the ipc
( shmmax SHMMAX 0X4000000)
i want grow this value but my ram is very short ...
where is the limit ? anybody know rules for the tuning on hpux 1020??
thank
pascal

[Steven E. Protter]

Guidelines. There are few rules:

http://search.hp.com/redirect.html?url=http%3A//forums1.itrc.hp.com/service/forums/questionanswer.do%3FthreadId%3D150477&qt=hpux+%2Btuning&hit=1

Patches are key:
http://docs.hp.com/hpux/pdf/5967-3577.pdf

Stretching now:
http://docs.hp.com/hpux/onlinedocs/netsys/0601_MWA-metrics.pdf

Good Luck,

SEP

[A. Clay Stephenson]

The rules for 10.20 are essentially the same as for any other flavor of UNIX. You can actually easily increase shmmax upto 1GB (which I suspect is well beyond your total virtual memory) and the system will run. Your real problem is that with so little memory you must have large amounts of swap, if you want to use large amounts of memory -- shared or private. In that case, there is really no point in talking much about performance tuning because your performance is going to be lousy.

You should be able to find additional memory for your old K-box at very reasonable prices on the used-equipment market.

In any event, the maxdsiz, maxtsiz, maxssiz, and shmmax limits are nothing more than "fence" values to prevent any one process from grabbing all the resources. The actual limits do not depend upon installed RAM but rather virtual memory (RAM + swap).
In your case, you definitely would want to set swapmem=0.

[Todd McDaniel_1]

Regarding Swap, I believe you can use FS as virtual swap...if you need additional.

Choose or make an unused filesystem and delegate it as swap. I will have to look up the documentation, but I believe it can be done thru SAM.

However, I wouldn't recommend it for permanent setup. only to get you to the point where you can add real swap.

[doug mielke]

With such limited memory you have few choices.
As noted, you'll want loads of swap space.

Another stratagy may be to experement with limiting the kernel param maxusers as a throttle.
Setting this one param sets some other important ones by default, keeping the kernel a bit smaller. The real benefit could come from preventing some processes from starting and overwhelming the system.
You'll get errors when they try, but what does run may run faster, and it could help you determine what apps are important and what aren't really necessary.

[Bill Hassell]

You can specify much larger limits for shmmax and let the programs use it...as long as you are willing to wait for VERY long periods of time. This is not something special with tuning. 128megs of RAM is far too small to ever be useful for HP-UX. You need 10x that much to be able to run anything useful without swapping. For example, with 128megs of RAM, running 5 programs might take an hour but the same 5 programs might finish in less than 2 minutes with 1000megs of RAM.

HP-UX is a virtual memory system so as long as you have plenty of swap space, and your users can afford to wait for very long periods of time, HP-UX will stop and swap portions of memory so that everything will run even though the programs are far too big to fit into physical RAM.