Harondel J. Sibble
Sat, 14 Dec 2002 10:52:28 -0800
On 14 Dec 2002 at 10:24, Henk Poley wrote:
> I'm not sure if this isn't some difference in the IDE vs. SCSI protocol,
Actually IDE is a dumbed down version of the scsi spec. Not this statement
doesn't apply the serial ata and serial scsi specs which oddly enough will
allow one to use serial ata drives directly connected to the serial scsi bus.
Not sure how they are pulling that one off.
> but SCSI drives are most of the times quite faster (and have lower
That depends, just like you have ata33, ata66, ata100 etc, there are also
speed scales in scsi: narrow (5 or 10mb/s), wide (20mb/s), ultrawide
(40mb/s), ultra2 (80mb/s), ultra3 aka Ultra160 (160mb/s) and Ultra 320 and I
think I just heard about Ultra 640 which is supposed to compete with Serial
Attached SCSI. In many cases the drive mechanism is identical to the ide
drive, they just have different interface boards. OTOH, there are some
drives that only exist in the scsi space and offer some serious raw
performance, however they are loud!!!, hot and VERY expensive.
Also you have to realize that the speeds above are not representative of the
drives themselve, but of the bus saturation. IOW, to really get U160 speeds,
you'd need multiple drives all using the scsi bus concurrently. This is one
of the great advantages of scsi in that the controller can talk to multiple
drives concurrently and the drives are smart enough that the controller can
give them a bunch of tasks and say, don't bother me again until you've
completed them all.
> They are also 1/4 to 1/2 the size for a disk you still can afford.
That's reasonably accurate although you can find some good deals on ebay. I
bought my Fujitsu 36gb Ultra2 drive for about us$100 a year ago that way.
The same drive here sold for about US$250.
Harondel J. Sibble
Sibble Computer Consulting
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