HP-UX Performance Issue

[Mladen Despic]

Hi Jamaludin,

Your 'swapinfo' output indicates that pseudo-swap is enabled. I think Oracle recommends that pseudo-swap be disabled as it competes with the database for locked memory resources.

To disable pseudo-swap, change the value of the kernel parameter swapmem_on from 1 to 0.

Mladen

[Mladen Despic]

Jamaludin,

If you disable pseudo-swap, you may want to add another 1-2 Gb of device swap. In fact, you may want to add device swap before disabling pseudo-swap.

Also, if you want to implement a number of configuration changes in order to improve your system performance, I would recommend making one change at a time. After each step, observe or monitor your system performance.

Hope this helps a bit.

[Magdi KAMAL]

Salam Alaikoum Jamaludin,

You may consider the following points :

1. If you are runnig OLTP applications and their is a lot of concurrent processes, Your swap space MUST be 3 to 4 times you memory capacity. ( I saw it's not the case on your configurations ). If you increase the swap, please do it on different disks for loadbalancing.

2. If you are not treating flat files and your applications are only doing database access, you MUST decrease the "Dynamic buffer max percentage" to 10 % and "Dynamic buffer min percentage" to 2 % . When this parameter ,db_max_pct, is set to 50 % ( default value from HP-UX installation) this means that the seystem could use 50 % from total RAM ( which will be 2 GB in your case ) in order to do lokk a head reading into memory. But if you are using only database and not flat files, this means that all you are reading and putting into memory is for nothing, and global degradation of the system appears.

3. What's about the size of your Oracle SGA allocated structure. This MUST be big enough to handle concurrent users without needs for swapping.

4. You need also to tune your shmmax, this could decrease the number of shared memory segments needed by HP-UX to handle the Oracle-SGA structure.

5. Oracle block size must be the same like hp-ux page size.

Hope this could help you.

Magdi

[Bill McNAMARA_1]

Performance analysis tools such as
Perfview/ Measureware and glance will allow you to identify if the problem is on disk io, cpu or memory or process. After this you can react accordingly.

Perfview is a free 60 day trial from software.hp.com and is good for time graph comparissons. No other analysis s/w is worth getting. PV is quite complete.

Later,
Bill