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server memory utilisation went to 95-98% even with less users login

 
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apple
Super Advisor

server memory utilisation went to 95-98% even with less users login

Dear HPUX gurus,
I would like to seek your advice. we have new database server HPUX 11.23i running latest oracle version (with oracle replication enabled to DR site). the memory is 32GB and it running financial application and we are at the testing stage. strangely, every time we started the oracle instances and start few connections from application, the memory utilisation went up to 90%. not much paging activity. wondering why only physical memory using and not using much of the paging space. how to optimise/improve the memory utilisation so that the application is faster.
have u experienced this? would really appreciate your advice. Many thanks in advance
4 REPLIES
Akif_1
Super Advisor

Re: server memory utilisation went to 95-98% even with less users login

Check the dbc_pct_max and dbc_pct_min kernel tunable parameter which causes a bottleneck memory issue , if it has default dbc_pct_max=50 change it to 15 or 20.

Follow below commands.

1. # kmtune -q dbc_pct_max

Note: The -q option displays information about the tunable.

2. # kmtune -s dbc_pct_max=20 =

Note: This will change the value.

3. # grep /stand/system

Note: Check new value is in the system file.

4. # config -u /stand/system

Note: Build the kernel and reboot.

5. # shutdown -ry 0


NOTE: Please note that the above steps require reboot of the system hence plan for a downtime.


Rgd's
T(ogether) E(very one) A(chive) M(ore)
Ishwar_1
Frequent Advisor

Re: server memory utilisation went to 95-98% even with less users login

Check size of the swap, is it tuned as per the Oracle Standard. Also check output of the top whether any process is going in zombie state, running and sleeping process.

Regards
Ishwar Venugopal
Steven Schweda
Honored Contributor

Re: server memory utilisation went to 95-98% even with less users login

> [...] latest oracle version [...]

Not a well-defined entity.

> [...] wondering why only physical memory
> using and not using much of the paging
> space. [...]

Huh? If there's still physical memory
available, why would the system want to use
the disk? As I understand virtual memory,
one tries to use physical memory until it's
all used, and then one starts to use the
disk (page/swap) to deal with what won't all
fit into physical memory.

Which of us is confused?
SoorajCleris
Honored Contributor
Solution

Re: server memory utilisation went to 95-98% even with less users login

If you are taling about performance issue,

Do you think your application is slow considering current system configuration?
( above 90% memory usage is not a bottle neck)


1. you system memory usage is above 90%
2. You cant see any swaping/paging ( This is actually good - this means there is no memory bottle neck)

This is not memory bottleneck, I have seen systems which runs with 99% memory usage and no swaping whole time.

Before giving some suggetions and action plans, you may need to check more data.
Did you check other resources? DISK, CPU and NTW?

To analyse memory usage , you may need to check which arena using memory ,
IS that system memory or application?

Then need to do trouble shooting.

Do you have any similar system which run the application to compare and contrast?

======
After analysing the usage, if you want to change dynamic buffercache, it is dynamic parameter in 11.23 . You can change that with out reboot.
=======================================================
# kctune |grep dbc
dbc_max_pct 50 Default Immed
dbc_min_pct 5 Default Immed
=======================================================

below is Oracle tuning doc
http://download.oracle.com/docs/html/B10812_06/chapter8.htm


Regards,
"UNIX is basically a simple operating system, but you have to be a genius to understand the simplicity" - Dennis Ritchie