Apple external SCSI drives

From: Stan Sieler <ss_at_allegro.com>
Date: Wed Jan 10 12:42:49 2001

Iggy asks:

> Granted, I forgot to mention that there are other SCSI setup utilities,
> but why in the world would one need to buy a drive /for/ a particular
> brand of computer? A hard drive is a hard drive is a hard drive.

Although they don't make them now, that wasn't always true for HP drives.
They claimed to have a (patented?) method of ensuring that if power failed
during a wite to a drive, no partial sector would be written. (This feature
as called "sector atomicity".) This was useful on their early/mid-1990s
PA-RISC systems (HP 3000, HP 9000) that had battery backup for the
system memory. A short (15 minutes or less) power outage wouldn't kill
the system. As the bean-counters took over, and dropped the internal
batteries (saving a small number of $$), HP stopped producing this kind
of system (instead, they started selling UPS for the entire system) and
they stopped making that kind of disk drive. Towards the
end, they were using Seagate (and Quantum?) drives with HP firmware.

(Note that I'm not claiming that it *worked*, nor that other drives
were really more likely to write a partial sector during a power fail!)

Now, "sector atomicity" is a forgotten phrase in HP, along with other ideas
like "the HP Way" :(


Stan Sieler sieler_at_allegro.com
www.allegro.com/sieler/wanted/index.html www.allegro.com/sieler
Received on Wed Jan 10 2001 - 12:42:49 GMT