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High Memory utilization

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jeevarajkn
Frequent Advisor

High Memory utilization

Guru's


Server-IA, HPUX 11.23, Oracle 10G, Flex Application, 12GB RAM, with around 300 users are connecting at a time.

I have noticed that my physical and virtual memory utilization is above 80% in all most time but there is performance issue has been reported yet.But shall I know any way to reduce the utilization as I have 12 GB RAM and secondary swap has been enabled and only 300 users are using at atime.

Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 12288 562 11726 5% 0 - 1 /dev/vg00/lvol2
dev 4096 561 3535 14% 0 - 1 /dev/vg00/lvol10
reserve - 12374 -12374
total 16384 13497 2887 82% - 0 -


TOP output
============
Memory: 9309372K (3606288K) real, 12695532K (4737400K) virtual, 110836K free Page# 1/17


morover could you plesae let me know what is - Page# 1/17


awaiting for your valuable tips.
9 REPLIES
jeevarajkn
Frequent Advisor

Re: High Memory utilization

Guru's

My dbc_max and dbc_min values are

Tunable Value Expression Changes
dbc_max_pct 10 10 Immed

Tunable Value Expression Changes
dbc_min_pct 5 Default Immed
Duncan Edmonstone
Honored Contributor

Re: High Memory utilization

I'm not really sure what you think your problem is here (memory is expensive - the more of it you use the better!) That said, I don't see any pseudo-swap... do you have it turned off for some reason?

Show output of:

kctune swapmem_on

HTH

Duncan

HTH

Duncan
jeevarajkn
Frequent Advisor

Re: High Memory utilization

Hi,

swapmem_on gives following out put.


Tunable Value Expression
swapmem_on 0 0

what does it means?


There is no performance issue reported till noe, but just want to know why this much of utilization as I have 12GN physical mem and only 300 users using the server.

Or its normal utilization.
Venkatesh BL
Honored Contributor

Re: High Memory utilization

You can check out http://docs.hp.com/en/B3921-90010/swapmem_on.5.html to know more about this tunable.
Duncan Edmonstone
Honored Contributor
Solution

Re: High Memory utilization

For most systems I would advise to use pseudo-swap and have swapmem_on set to 1 - I don't know if there's a specific reason why you don't have this set to 1, but someone must have specifically set it to 0 as the default is 1 - If you have colleagues who know the history of this system maybe they can tell you...

Be aware however that changing this to 1 will require a reboot...

> There is no performance issue reported
> till noe, but just want to know why this
> much of utilization as I have 12GN
> physical mem and only 300 users using the
> server.

There's almost no way anyone can help you with that as we know nothing about your application or database, or the queries that run in it... for all we know this may be perfectly normal, or it may be way out of whack. What I would say is that you certainlky shouldn't assume that this means that each user requires ( 12GB * 80% ) / 300 memory - Oracle sets aside a whole bunch of memory when it starts even if no users are connected.

If you really want to track this in a useful fashion you should write a script to record the number of users in the database and memory utilized at any given time - as I don't know what tools you have or how you figure out the number of users in your system, it's difficult to suggest how right now...

HTH

Duncan

HTH

Duncan
Ganesan R
Honored Contributor

Re: High Memory utilization

Hi,

Where do you see that physical memory is utilised above 80%? Anyway, important question here is, why do you feel that above 80% utilisation is performance issue?

We paid for 100% resources available on the server and we suppose to utilise 100%. If the resouce utilisation is reached 100% then we can think about further.

There are many things involved to utilise the resources not just only the users as you specified. There are applications more cpu bound, some applications need more memory. You need to analyse all these data and act accordingly.

Best wishes,

Ganesh.
jeevarajkn
Frequent Advisor

Re: High Memory utilization

Duncan,


Pls correct me if I am wrong....

If am enabling the swapmem_on, psuedo swap will enabled and it will reduce the swap reserved memory (reserve - 12374 -12374).
Duncan Edmonstone
Honored Contributor

Re: High Memory utilization

no it won't reduce "reserved memory" - that memory will always be "reserved" - that's the way the VM subsystem works... but it's not "used" so you don't need to worry about it.

HTH

Duncan

HTH

Duncan
jeevarajkn
Frequent Advisor

Re: High Memory utilization

Dear Guru;s


Thanks for the repply, am closing this thread.