topic Re: System Memory issues in Operating System - HP-UX

System Memory issues

hpuxrox — Thu, 08 May 2008 13:26:54 GMT

I have a system that has some major memory issues.

# vmstat 30 5
procs memory page faults cpu
r b w avm free re at pi po fr de sr in sy cs us sy id
3 1 0 2307670 1116505 636 72 16 0 0 0 30 11017 299230 10495 45 10 45
1 0 0 2293300 1108170 558 55 17 0 0 0 0 2527 47355 2093 24 5 70
3 0 0 2260420 1106476 431 52 1 0 0 0 0 2525 62553 2064 30 6 63
2 0 0 2221641 1106970 364 47 0 0 0 0 0 1832 33276 1605 25 5 70
3 1 0 2276671 1106881 407 54 1 0 0 0 0 3655 57495 3467 37 5 58
#

Re: System Memory issues

Patrick Wallek — Thu, 08 May 2008 13:44:08 GMT

>>I have a system that has some major memory issues.

OK. So what do you want? You have provided no real information about your system. It could be helpful to know if this is HP-UX and if so, what version.

It could also be helpful to know what applications are running.

How do you know you have "major memory issues"?

According to the vmstat output you are not paging out, which is good. 'swapinfo -tam' output could be helpful. If you have Glance installed, you can use it to get a better picture of your memory usage.

Until you provide more information, I don't see how we can provide much help.

Re: System Memory issues

hpuxrox — Thu, 08 May 2008 13:56:24 GMT

Done know. Not my system. Just picked it up. Ill i know at this point is its crashing because of memory. I'm researching.

# swapinfo -tam
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 12288 0 12288 0% 0 - 1 /dev/vx/dsk/rootdg/swapvol
reserve - 8539 -8539
memory 32738 22076 10662 67%
total 45026 30615 14411 68% - 0 -
#

Re: System Memory issues

Safarali — Thu, 08 May 2008 14:10:27 GMT

Hi
From your swapinfo -tam out put showing that you are shortage of swap memory
identify the process by using top command
if the process is not need kill it

or you have to add additional swap space if it is a day to day problem

Regards
Safar

Re: System Memory issues

Steven E. Protter — Thu, 08 May 2008 14:27:23 GMT

Shalom,

Based on still scant information you have two choices.

1) Add swap and get to a normal ratio of swap verus memory 1.0 or 1.5 to 1.

2) Throw more memory at the problem.

I suggest both.

SEP

Re: System Memory issues

Patrick Wallek — Thu, 08 May 2008 14:29:18 GMT

>>Ill i know at this point is its crashing because of memory

How did you determine that? Is the whole server crashing and restarting?

Does anything show up in /var/adm/syslog/syslog.log or /var/adm/syslog/OLDsyslog.log. What about /etc/shutdownlog?

If it's crashing is a crash dump being generated? If so, you probably should get that analyzed by HP.

Re: System Memory issues

Patrick Wallek — Thu, 08 May 2008 14:31:05 GMT

I'm not convinced it's a swap space issue. You have pseudo-swap turned on, so unless you have more than 45GB of RAM, I think your swap configuration is OK.

Re: System Memory issues

Don Morris_1 — Thu, 08 May 2008 15:57:24 GMT

Sorry, I don't see a memory issue here. pi ranges from 17 down to 1 in this output and po is consistently 0. So you aren't paging out.

free is around 110xxxx -- assuming a 4K page size (the usual), that's around 4.2+ Gb just hanging around. Your later swapinfo output implies your system has in the 40Gb range, so that means 10% of the memory is free.

Your swapinfo output shows virtual address space utilization, but nothing terribly excessive (you still have 14411Mb of swap to reserve/use, after all).

If you clarify the HP-UX version and just what is "crashing because of memory" (if it is an application, what's the exact crashing state/error? Is it getting ENOMEM from a system call? If so, which one? etc.), folks could help you more... the output given doesn't really indicate a problem.

Re: System Memory issues

Bill Hassell — Thu, 08 May 2008 16:30:42 GMT

It is really important to define "crash". Normally, the term crash is used when describing an HP-UX panic where the OS halts, writes memory to a dump area and then reboots. If instead you mean that an application is aborting with a core dump, then this is an application issue and not something you can fix as an admin other than to increase run-away program limits. HP-UX is a virtual memory system so you can run very large programs that are properly written and compiled. But as mentioned before, if a process runs out of memory, the issue is with the program and what it is trying to do. If your program is only a 32bit executable, then the programmer should be well aware of the limits imposed by not writing a 64bit program. You can increase maxdsiz in the kernel but your program may need to be recompiled or possibly changed using chatr to access a larger memory map.