Doug White wrote in list.freebsd-current:
> On Tue, 10 Aug 1999, Oliver Fromme wrote:
> >
> > Do those drives happen to be IBM DeskStar drives?
> > They spin down automatically when they have not been turned
> > off for about a week, in order to clean the heads.
> > It's a feature.
>
> You've got to be kidding.
No, I'm serious, that behaviour is a fact, and it's documented.
> That makes them totally useless for server
> operation
The IBM DeskStar series is for desktop use, not for Servers.
(Apart from the fact that I wouldn't use IDE drives for real
servers anyway.)
> -- at some random time every week, down goes your server for a
> few minutes. :(
No, only a few seconds. If there doesn't happen to be a disk
access in that time interval, you won't notice at all. Other-
wise you'll get that log message from the driver.
This is the background of that feature: The IBM DeskStar disks
are specifically designed for at least one on/off cycle per
day. The "landing zones" where the heads are parked consist of
a special layer that cleans the heads. If the disk is not
switched off for a long period, the disk enforces a short spin-
down + spin-up to clean the disk heads periodically. All of
this is explained in more detail in a white paper of IBM, I
think it is available from IBM's site.
IBM's server disks (UltraStar) are designed for much fewer
on/off cycles (in fact IBM recommends that they should not be
used in desktops that are switched off very often, e.g. for
power-saving or noise-reduction). They don't have that
cleaning layer (and they don't need it). That's one of the
reasons why they're more expensive.
Bottom line: For a server, buy server disks. If you use
cheap IBM DeskStar disks in a server, you won't get 100%
availability (rather 100% minus a few seconds per week).
Regards
Oliver
--
Oliver Fromme, Leibnizstr. 18/61, 38678 Clausthal, Germany
(Info: finger userinfo:[EMAIL PROTECTED])
"In jedem St�ck Kohle wartet ein Diamant auf seine Geburt"
(Terry Pratchett)
To Unsubscribe: send mail to [EMAIL PROTECTED]
with "unsubscribe freebsd-current" in the body of the message
