Re: How to improve db performance with $7K?

Sorry if I'm pointing out the obvious here, but it seems worth
mentioning. AFAIK all 3ware controllers are setup so that each SATA
drive gets it's own SATA bus. My understanding is that by and large,
SATA still suffers from a general inability to have multiple outstanding
commands on the bus at once, unlike SCSI. Therefore, to get good
performance out of SATA you need to have a seperate bus for each drive.
Theoretically, it shouldn't really matter that it's SATA over ATA, other
than I certainly wouldn't want to try and cram 8 ATA cables into a
machine...

Incidentally, when we were investigating storage options at a previous
job we talked to someone who deals with RS/6000 storage. He had a bunch
of info about their serial controller protocol (which I can't think of
the name of) vs SCSI. SCSI had a lot more overhead, so you could end up
saturating even a 160MB SCSI bus with only 2 or 3 drives.

People are finally realizing how important bandwidth has become in
modern machines. Memory bandwidth is why RS/6000 was (and maybe still
is) cleaning Sun's clock, and it's why the Opteron blows Itaniums out of
the water. Likewise it's why SCSI is so much better than IDE (unless you
just give each drive it's own dedicated bandwidth).
--
Jim C. Nasby, Database Consultant               decibel@decibel.org
Give your computer some brain candy! www.distributed.net Team #1828

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