IDE x SAS RAID 0 on HP DL 380 G5 P400i controller performance problem

Hi people,

I have a particular performance problem under a system installed.

In the lab I have an old Microside + Dual Core machine 1GB RAM with 40gb HD IDE and
a newer machine HP DL 380 G5 4GB RAM and 500GB SAS under RAID 0 (4 disks) P400i Smart Array Controller.

**Both with Linux Kernel 2 .4.37.9 and Postgresql 7.2**

Under a insertion test we get a performance of 2.5 secs under 2000 inserts (table with a single char(50) column) in the IDE disk.
And 500GB RAID 0 (4 disks!) and 37.5 secs under the same test!

I tried:
- All the postgresql.conf tuning possibles
- All the kernel tuning values possibles
- fstab mount options
- limits.conf values
- I/O tests with boonie++ that shows that P400 is superior than IDE - as expected
- 'massive' Google search combinations without answers
- Mandriva 2009.1: result is about 12 secs (but it need to be kernel 2.4 with PGSQL 7.2)


The real case:
~100k database insertions that runs in 2 min in the IDE, against ~40 minutes (P400i) in the HP.

The same test in the HP Blade G5 P200 controller works fine.

Thanks for any answers/analisys.

Best regards.

--
Daniel Ferreira