On 6/28/05, Richard Welty <[EMAIL PROTECTED]> wrote:
> On Tue, 28 Jun 2005 16:10:32 -0400 Jason Crawford <[EMAIL PROTECTED]> wrote:
>
> > If you want the closest you can get to SCSI without actually going
> > SCSI, try the LSI Logic MegaRAID SATA 300-8X controller. It uses the
> > SATA-II spec, so you get 3.0gbps throughput, plus you have NCQ, which
> > can queue up to 32 commands (IIRC). It's still no U320 SCSI setup, but
> > it's much much much better than PATA or even SATA-I, which is half the
> > speed, and normally doesn't support NCQ at all.
>
> recent discussion on one of the PostgreSQL lists suggests that at the
> current state of the art, SATA and SCSI are about comparable for
> read intensive ("SELECT") operations, but SCSI still outperforms
> SATA for write intensive ("INSERT" and "UPDATE") operations.
>
> additionally, i saw someone mention RAID 5 in there somewhere. RAID
> 5 is fine for read operations, but RAID 10 will outperform it in write
> intensive operations.
>
> so if i were managing a lot of disk i/o (say, a really really huge,busy
> mail server), i'd probably look at RAID 10 with a good SCSI array.
>
The main reason I suggested SATA-II is because the OP said he can't do
SCSI, but still wants a good RAID. Granted, 32 commands is still not
even close to the 256 commands SCSI is capable of (IIRC), but it's the
closest thing, and much cheaper. SATA-II is still new technology as
well, so a place that is absolutely dependent on data will have the
money for SCSI RAID1+0, no problem, as it's tried and true technology,
as well as still the fastest. However the OP talked about rebuilding a
server on a home network, and a RAID1+0 U320 SCSI array is just too
damn expensive for that (IMO). Unless his home network runs an
extremely busy news server or database server, SATA-II RAID5 (or even
1+0 if you don't mind losing half the disk space) is plenty, since
it's 3.0Gbs, and can queue up to 32 commands. I highly doubt he'll be
maxing that out any time soon, and you can get 160GB SATA-II disk for
under $90, good luck finding a U320 SCSI disk close to that size for
even close to that price.
Jason
