[PLUG] SCSI verses SATA RAID

[Steve Bonds]

On 3/31/06, Roderick A. Anderson raanders-at-acm.org wrote:

> What are your thoughts on SCSI verses SATA RAID?

I'm a SCSI bigot from way back, but the price point on SATA is just
too compelling these days.  A while back SATA crossed the "costs half
as much for the same capacity" mark, which is important since it means
you can now own a mirrored pair of SATA drives for about the same
price as a single SCSI drive.

A quick Pricewatch search on 5-year warranty drives (Seagate) at 300GB
shows this today:

SCSI: $500
SATA: $120

Based on this approximation, I could own *four* SATA drives for the
price of a single SCSI drive, under the same warranty.  The SCSI drive
is 10,000RPM, and the SATA 7200RPM, but with four drives I can now run
a striped/mirror arrangement ("RAID-10") and those two pairs of
7200RPM drives will outperform the 10,000RPM drive due to the RAID
involved.

I frequently hear RAID rebuild time as a reason the individual drives
need to be more reliable.  The probability of having a second drive
fail during the 2-3 hours (at most) it might take to rebuild onto a
hot spare (hey, you can afford one now!) is very low.  Far lower than
the probability of a second SCSI drive failure during the 3-5 days it
will take to order a new drive, since you couldn't afford a hot spare.

As painful as it is for a "quality-conscious" person such as myself to
think about, once RAID comes into play, the "I" (inexpensive) is the
important part.  Unless the failure rate is truly ridiculous (and the
warranty prevents that) the cheaper, the better.

  -- Steve