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On Sun, 24 Nov 2002, Russell Coker wrote:

> IDE and SCSI give very similar performance.  Performance is determined by 
> hardware issues such as rotational speed rather than the type of interface.
I agree if you think at a single drive workstation, not if you think at a 
server with many disks making heavy i/o on the disks.

ATA/IDE drives/controllers lack the ability to perform "command queuing",
so they are not much fast on many concurrent i/o requests (this feature
will be introduced in serial-ATA II devices, I think)

SCSI can queue up to 256 commands and reorder them for maximum
performance, furthermore SCSI has been developed to be used in the server
market, so they are optimized for servers (rescheduling commands and seek
patterns of SCSI has been written for this kind of use!)

It's true that on many entry-level severs IDE is enough for the job (and
a lot cheeper than SCSI), but on hi-end servers scsi is still a MUST!

btw, rotational speed speeking, how many 15.000 rpm IDE disks are
there? :-)

emilio brambilla

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