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

> > **Both with Linux Kernel 2 .4.37.9 and Postgresql 7.2**
>
> Wow. You really need to upgrade.
>

Yes, but unfortunately, actually it's impossible and economically
inviable...

> > 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!
>
> Is each insert in its own database transaction? (That is you've
> done nothing to BEGIN a transaction, do the inserts, and then
> COMMIT?) If so, you're old IDE is lying to PostgreSQL when it says
> it has committed each insert. If you pull the power cord on the
> computer a few times during this insert test, you'll find you wind
> up missing rows which were supposedly inserted, and you will likely
> have database corruption, which might render the database totally
> unusable.
>

It's a single inserts.sql with 2000 inserts.
But it's interesting test, I'll check the inserted data if it exist or not.
Maybe it's inserting only in RAM and not at disk and this nice performance
is fake.

> If you implement your RAID with a good controller which has a
> battered backed-up RAM cache, and that is configured to write-back,
> you'll see much better performance.
>

I'm working on it.. a have been seen posts in the web of people saying
things
about the BBU in P400i be disabled by default. Or problems with older
version of kernel module (cciss) turn it off by some kind of
incompatibility.

Search the archives for BBU and you'll find many other discussions
> of this.
>
> -Kevin
>

Thanks, Kevin.

--
Daniel Ferreira