On Jul 12, 2006, at 12:56 PM, Daniel da Veiga wrote:
On 7/12/06, mos <[EMAIL PROTECTED]> wrote:
At 12:42 PM 7/12/2006, you wrote:
>On Tuesday 11 July 2006 19:26, mos wrote:
> > SCSI drives are also designed to run 24/7 whereas IDE drives
are more
> > likely to fail if used on a busy server.
>
>This used to be the case. But there are SATA drives out there
now being made
>for "enterprise class," 100% duty cycle operations. See, for
example,
>http://www.westerndigital.com/en/products/Products.asp?
DriveID=238&Language=en
>
>No, I am not affiliated with WD, just had good experience with
these drives.
>1.2 Million Hours MTBF at 100% duty cycle and a five year
warranty. Not bad.
That's good to hear, but MTBF is really a pie in the sky
estimate. I had
an expensive HP tape drive that had something like 20,000 hr MTBF.
Both of
my units failed at under 70 hours. HP's estimate was power on
hours (unit
powered on and doing nothing), and did NOT include hours when the
tape was
in motion. Sheesh.
To get the MTBF estimate, the manufacturer will power on 100
drives (or
more) and time to see when the first one fails. If it fails in
1000 hours,
then the MTBF is 100x1000hrs or 100,000 hours. This is far from being
accurate because as we all know, the older the drive, the more
likely it is
to fail. (Especially after the warranty period has expired,
failure rate is
quite high<g>).
I am hoping the newer SATA II drives will provide SCSI performance
at a
reasonable price. It would be interesting to see if anyone has
polled ISP's
The answer (short and based on experience) is NO! A SATA drive is no
different from an IDE drive of the same type. I'm sure they'll release
fast and reliable drives based on SATA with differenct mechanisms
(like the one Joshua pointed), but most will be IDE like with a
different interface, those high demand drives are fated to cost a lot
more.
Rule of thumb: If you see a SATA drive that is 18GB, 36GB, 72GB, or
144GB and costs WAY more per GB than other SATA drives of more normal
capacities (80GB, 100GB, 120GB, 160GB, 200GB...) then it's probably
using the same physical drive as a SCSI drive but with a SATA
interface tacked on instead.
That is something only an ISP or corporation would give (and no one
will EVER sign it, *lol*). SCSI has one more advantage I forgot to add
to my previous message, they can be arranged better in RAID with hot
swap. I can only tell about my company, where servers have all SCSI
disks (IBM, Dell).
Have you had any specific problems with SATA/PATA hot-swap? We've
only had problems when we've tried to use a ThreeWare RAID card and
tried to do hot-swap...
-JF
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