topic SOS!! "upc pages" continually increase!! in Operating System - Tru64 Unix

SOS!! "upc pages" continually increase!!

aven_guo — Tue, 30 Nov 2004 03:44:49 GMT

My es40 with 5.1b encounter a problem!
Our free memory cost down continually and i find the "upc pages" increase by "vmstat -P",what can i do!!!
our free memory will dispear soon!!
how to flush "upc pages" safely or how can i find out which process cost the related memory.
out machine can not reboot!

Re: SOS!! "upc pages" continually increase!!

aven_guo — Tue, 30 Nov 2004 03:47:32 GMT

sorry,it is "ubc pages"

Re: SOS!! "upc pages" continually increase!!

Michael Schulte zur Sur — Tue, 30 Nov 2004 04:11:42 GMT

Hi,

ubc stands for unified buffer cache and belongs to the operating system. You can get the current value with sysconfig -q vm. The value to look for is ubs_maxpercent. It can be set with sysconfig -r vm ubs_maxpercent=newvalue. This is not really a problem unless you have page out.
Have a look at man sys_attrs_vm

greetings,

Michael

Re: SOS!! "upc pages" continually increase!!

aven_guo — Tue, 30 Nov 2004 04:25:17 GMT

thank u!!!
this parameter can modify online?

Re: SOS!! "upc pages" continually increase!!

Michael Schulte zur Sur — Tue, 30 Nov 2004 04:54:59 GMT

Hi,

the star in the manual pages indicates that this parameter can be changed online.

greetings,

Michael
ps. So far you have not assigned any points to the answers of those who tried to help. Please read the following and take a minute to do so. Thanks!
http://forums1.itrc.hp.com/service/forums/helptips.do?#28

Re: SOS!! "upc pages" continually increase!!

Hein van den Heuvel — Tue, 30 Nov 2004 19:19:50 GMT

Steven, You probably do not have a real problem. It just looks scary :-).
The default ubc_max is really high.... like 100%... version dependend. But it just says 'use all memory unless something else needs it more'. It will give it away if needed!

Like Michael wrote "This is not really a problem unless you have page out."

Go ahead, turn it down some if that make you feel more comfortable. In fact you really should try to turn it down. See how the system reacts, see how more free memory appears and nothing else changes, and then turn it back up in the knowledge you can control it if and when you feel that is needed. But hey, you have all this memory, why have it free, just use it to buffer some file data if (and only of) there is nothing else that needs the memory.

Don't worry, Be Happy!

Hein.