On Wed, 3 Feb 1999, Jon Fraser wrote:
> I know someone will bring up using SCSI vs IDE drives. As far
> as SCSI vs UIDE goes, I've seen sustained data rates of
> 8mbytes/second and up to 90 transfers/second from our UIDE
> drives. Interrupt utilization seems to be a bit higher than
> scsi, as our IDE drives/controllers can only tranfser 16 blocks
> at a time. So, I don't think that the IDe drives are your
> bottleneck.
SCSI vs IDE isn't a question of throughput, its a question of concurrency.
IDE can only support 1 device in operation per channel at any given time.
So, in a system with 4 IDE drives, only 2 can be doing anything useful at
any given time. On a SCSI system with 4 drives, all 4 drives can be busy
at the same time. And even better, you can go beyond 4 drives.
So, obviously, SCSI shows its true advantages when you get a system that
has more than 2 drives (but, if you have 2 ide drives, make sure one is on
the primary channel and the other is on the secondary channel!).
Also, in terms of performance, more drives is better. For a 16 gig cache,
you are better off with 4 4gig drives than 2 8gig drives, and MUCH better
than 1 16gig drive.
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Received on Wed Feb 03 1999 - 19:57:21 MST
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