Re: tlug: new small scsi hard drive

["Marc E. Christensen" <marc@example.com>]

On Wed, 2 Jun 1999, Jonathan Byrne wrote:

> These days, SCSI and IDE drives are generally mechanically the same,
> with only the drive electronics being different.  On a single drive
> system, you'd be hard put to notice a performance difference.  On a
> dual-drive system, you can put one IDE drive on each header and probably
> see superior performance to two SCSI drives attached to the same SCSI
> adapter.  If there are two IDE drives on the same header, UW SCSI might
> have somewhat of an edge, but I'm not sure.  For drive performance, I
> see little reason to use SCSI in a desktop machine.  The nice things
> about SCSI are that you can hook a lot of devices up to one adapter, and
> they aren't limited to only disks, so you can put a scanner and tape
> drive on there as well.

Some other benifits of SCSI over IDE are hardware error recovery, command
tag queueing, 7 or 15 devices/channel (some cards have up to 3 channels)
and accessing multiple devices simultaniously (nessasery for raid)..  Yet,
like you mentioned, IDE is the way to go for systems which will only have
one or two drives and/or devices total.  If you are going to run more than
two (modern)  drives then the benifits of SCSI start to play a large role.
I choose SCSI for servers and high-end workstations.  low to medium end
workstations benifit more from the redused cost of IDE.

Even the beowolf clusters that I have worked on only use IDE (UDMA) on
the compute nodes.  The master server and file servers usualy are SCSI
because they need the speed in disk IO.  Compute nodes usually have only
one disk.

--
Marc C.
http://www.mecworks.com

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