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Subject: Re: storage bits
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Date: Mon, 16 Sep 2002 21:11:47 +0200 (CEST)

On Mon, 16 Sep 2002, Stephen D. Williams wrote:

> It's efficient-end, not low end.  At 1Million hour MTBF, 133MB/sec,
> and pretty good buffering and speed, the only thing going for SCSI is
> 15,000 RPM vs. 7200 and in a very small number of cases, slightly
> better scatter-gather.  (Actually, I think there might be a 15,000 RPM
> IDE now.)

It's not just krpm, the desktop HDs have a higher failure rate. But I
agree, EIDE has high density, and EIDE hardware RAID can offer SCSI a
sound beating for reliability, performance, and storage density/rack units
for the money, if designed for it, and if people would actually start 
buying it.
 
> The other issues are pretty much non-issues: using multiple drives and
> controller contention (just use many IDE channels with extra PCI
> cards, up to 10 in some systems), and long cable runs (just split

There are not all that many hard drives inside an 1U enclosure. Airflow
blockage (you have to fit in 2-3x the number of SCSI disks with EIDE) will
soon be a thing of the past due to SATA.

> storage between nodes).  Dual-port SCSI is also a non-issue since it
> is very expensive, doesn't work that well in practice because there
> are numerous secondary failure modes for shared disk systems, and
> because you still end up with a single point of failure.

Since rack-space costs dominate, and our systems need more or less decent
I/O we're going with 1U Dells with SCSI. The hard drive prices don't
really make a visible difference, given the cost of the iron, and the
rackspace/month. Plus, 1U Dells don't have any space left for lots of EIDE
drives.


