Multiple hard disk failures - coincidence ?

[Bernd Walter]

On Sun, Dec 19, 2004 at 08:07:20AM +1100, Peter Jeremy wrote:
> On Sat, 2004-Dec-18 20:59:11 +0100, Bernd Walter wrote:
> >On Sat, Dec 18, 2004 at 08:17:39PM +1100, Peter Jeremy wrote:
> >> My approach to this is to add a line similar to 
> >>   dd if=/dev/ad0 of=/dev/null bs=32k
> >> for each disk into /etc/daily.local (or /etc/weekly.local or whatever).
> >> This ensures that the disks are readable on a regular basis.
> >
> >Regular reading of every file is part of what I call backup.
> 
> That only verifies the used part of the disk.  Reading the unused parts

That's true - used parts are the only I'm interested in reading.
If blocks fail that aren't used write reallocation has to do it's
job.

> of the disk as well helps reduce surprises.  Also, in a mirrored environment,
> the backup does not ensure that the data can be read off both disks.
> (Or the parity area for RAID-5).

Raid is another story.
Just dd'ing the disks wouldn't check redundance integrity, but if you
check the integrity why would you still want to check via dd too?

-- 
B.Walter                   BWCT                http://www.bwct.de
bernd at bwct.de                                  info at bwct.de