RE: [9fans] plan 9 ports to unix (including libdraw)

["Nigel Roles" <nigel@9fs.org>]

9fans-admin@cse.psu.edu wrote:
>>> real data.  Especially now that my Venti server is mirrored
>>> across two different-model 200GB IDE drives.
>>
>> How about IDE problem which Niger wrote.
>
> That's why I'm mirroring across two different-model 200GB drives.
> The theory is that they're not that likely to fail simultaneously.
> If you believe that a drive will fail once a year (which I think is
> high) then two drives independently failing together will happen once
> every few centuries, which is low enough that I can worry about
> other problems, like my apartment catching fire.
>
> Russ

It's certainly true that simultaneous failures are unlikely, and
you should check your fire extinguisher in your apartment, but I
think Geoff made the point a while back that the probability of
failure for every given day is not 1/365.25; it starts high,
drops to near zero, and then climbs rapidly in the few months before
the warranty runs out. This is the "bath tub reliability curve".
Also, if I cannot get to my machine for a few weeks, this
significantly widens the window for a simultaneous failure.
I think a few centuries is optimistic.

In my case I'm more interested in having someone else already
worked out how to replace and rebuild a drive when it fails, hence
a need for a reputable RAID BIOS.

Mentioning no names, our experience with SCSI U320 drives (i.e.
the des. res. drives of the moment) is that price is not a guide
to reliability.