Swapping space critical on DB servers

[Fenglin]

hi

In what circumstances will we receive swapping space critical on DB servers? What does this alert mean?

Regards
Feng Lin

[Johnson Punniyalingam]

in term of "Performance issue" -> too much work load to DB Server,

or improper - Kernal parameter settings

[Fenglin]

How to know whether there are improper kernel settings?

In terms of performance, we added a few more jobs on the DB servers but they are schedules at different timings when we receive the alerts. That is why I need your help to throw me more light into this issue.

Regards
Feng Lin

[Johnson Punniyalingam]

for more information

http://www.dba-oracle.com/t_server_swap_space_allocation.htm

[Johnson Punniyalingam · Accepted solution]

>>we added a few more jobs on the DB servers but they are schedules at different timings when we receive the alerts. That is why I need your help to throw me more light into this issue<<

Yes - I can shed some light on OS portion only

suggestion and recommendation related to oracle you cross check with oracle support,

how much is your memeory installed

dmesg |grep -i pshyical

swapinfo -mat

what OS version?

uname -a;model

what are your currnet parmeter settings

Based on above output hope you can also shed some light on better understanding of your problem

[Fenglin]

can too many queries on the DB servers cause swapping space critical? or just high cpu alerts ?

I ask this because after a recent project cutover, we are receiving these alerts which we do not receive before. Our DB servers are serving customers online as well.

The main point is do we need to add memory on our DB servers ?

[Aneesh Mohan]

Hi,

>>can too many queries on the DB servers cause swapping space critical? or just high cpu alerts ?

Yes , PGA memory is a swappable memory,if your DML operations required more PGA work area to complete ,I belive it can demand more swap memory.

How much is your swap memory utilisation ?

Aneesh

[Johnson Punniyalingam]

>>The main point is do we need to add memory on our DB servers ?<<

Performance - Not only based on the adding memory will not solve you issue,

As mentioned on above post if you could provide information asked , hope we can give some suggestion

reason for asking "performance" issue could be many reason it depends all factors ,

CPU,Memory,Swap,Kernal settings,disk, patches.. etc

I would suggestion if you escalte this issue to DBA admin, hopefully they could give clear picture - hence database inputs also important

Hope this helps

Johnson

[Fenglin]

I got the following info on the server

swapinfo -mat
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 12288 4534 7754 37% 0 - 1 /dev/vg00/lvol2
reserve - 7749 -7749
memory 12721 8340 4381 66%
total 25009 20623 4386 82% - 0 -
uname -a;model
HP-UX nspppdb1 B.11.11 U 9000/800 1236689390 unlimited-user license;9000/800/rp4440

There is no info when i do 'dmesg|grep -i physical

Please advice.

[Aneesh Mohan]

Hi,

You need more swap memory.

To get available physical memory:-

# echo phys_mem_pages/D | adb64 -k /stand/vmunix /dev/mem
phys_mem_pages:
phys_mem_pages: 524288 ---> multiply the value by 4096 to get in bytes


# bc
524288 * 4096 /1024/1024
2048 ------> 2GB physical memory


regards,
Aneesh