Re: hardare config question

Erik,

I think you have a mismatch in your Linux driver and firmware for your 3Ware
card. Download a matched Linux driver and firmware from www.3ware.com and
your problems should disappear.

- Luke

On 4/28/06 8:37 AM, "Erik Myllymaki" <erik(dot)myllymaki(at)aviawest(dot)com> wrote:

> This is a question that I also posted on Dell hardware forums, and I realize
> it
> probably belongs there more than here. But I am thinking someone might have
> some anecdotal information that could help me and this post may help someone
> else down the road.
>
> My PowerEdge 1800 (dual 3ghz Xeon, 3GB ram) came with a single SATA drive. I
> installed and developed a modest database application (Postgresql, Windows
> 2003
> Server, Python) on it and was pretty impressed with the performance.
>
> I wanted to add some more space, speed and reliability so I bought a used
> 3ware
> 9500s SATA raid card. I bought three more of the same drives (Seagate
> ST3808110as) and configured them in RAID 5 (3 in RAID one as hot spare). I
> reinstalled the OS and software (my efforts to ghost were not
> fruitful...another story), and the first thing I did was run a sql script to
> make tables, indexes, sequences etc for my app and import about 20MB of data.
>
> When I had this installed on a single SATA drive running from the PE1800's
> on-board SATA interface, this operation took anywhere from 65-80 seconds.
>
> With my new RAID card and drives, this operation took 272 seconds!?
>
> I did a quick search and found a few posts about how RAID 5 with Databases is
> a
> poor choice and one in particular about Postgres and how you could expect
> performance to be halved with RAID 5 over a single drive or RAID 1 (until you
> get above 6 disks in your RAID 5 array). So, a poorly planned configuration on
> my part.
>
> I scrubbed the RAID config, made two RAID 1 containers (also read about how
> moving database logs to a different partition than the database data is
> optimal
> for speed and reliability). I installed the OS on the first RAID 1 volume, the
> Postgresql apps and data on the other, and used Junction from sysinternals to
> put the pg_xlogs back on the OS partition (does Postgresql have an easier way
> to do this on Windows?).
>
> Well, things didn't improve noticeably - 265 seconds.
>
> Next step, turn on the 3ware RAID card's write cache (even though I have no
> Battery Backup Unit on the RAID card and am warned about possible data loss in
> the event of power loss).
>
> This helped - down to 172 seconds.
>
> Is this loss in performance just the normal overhead involved when adding a
> raid card - writes now having to go to two drives instead of one? Or maybe is
> the SATA interface on the Dell 1800s motherboard faster than the interface on
> the 3ware raid card (SATA II ?).
>
> Thanks for any help you guidance you can provide.
>
> ---------------------------(end of broadcast)---------------------------
> TIP 3: Have you checked our extensive FAQ?
>
> http://www.postgresql.org/docs/faq
>
>