Re: Hardware needed for 15,000,000 record DB?

>>>>> "Jeremy" == Jeremy Buchmann <jeremy@wellsgaming.com> writes:

Jeremy> Curt Sampson wrote:
>> On Mon, 22 Apr 2002, Jeremy Buchmann wrote:
>>
>>> You minimize the amount of time the I/O takes by using fast
>>> storage devices.  This means SCSI.
>>
>>
>> Not necessarially. More disk arms is also a big help, so much so
>> that I would take two IDE drives (assuming that they're fast modern
>> ones) over one SCSI drive any day.

Jeremy> SCSI also has several other advantages...it doesn't suck up
Jeremy> all your CPU time when there's a lot of disk activity, and it
Jeremy> supports command queueing.  IDE was designed to be cheap, SCSI
Jeremy> was designed to be good.  I've used both and from my
Jeremy> experience, SCSI is The Way.

Well... I wouldn't phrase the problem that 1-dimensionally.  There are
IDE drives that support queueing (IBM Deskstar something-or-other) and
some OSs have ATA controller code that really kicks but (FreeBSD, for
instance), so from a software point of view, IDE can work well.

It's even likely that the maufacturing process is nearly identical for
some makes and models.

But the RMA rates for _extreme_ usage don't match.  My theory:

I find that IDE drives placed in situations where their request queue
is populated completely for days at a time will fail between 3 and 6
months where SCSI drives can last years in this condition.  Pay
attention to the qualification: we're talking not even a milisecond of
unused time for at least hours on end out of a day.

I believe this is due to the SCSI disk having software that will
momentarily stop processing requests to perform a recalibration
... where IDE drives may only do this when they are idle for some
small period of time.

Dave.

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|David Gilbert, Velocet Communications.       | Two things can only be     |
|Mail:       dgilbert@velocet.net             |  equal if and only if they |
|http://daveg.ca                              |   are precisely opposite.  |
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