On Sun, 2007-02-11 at 17:27 -0600, Kim Elmore wrote:
> I use a RAID for just this purpose. And I have a spare disk and RAID
> controller on hand, in case either the disk or the controller goes
> South.
Whilst RAID is indeed an excellent idea and not too expensive at today's
HD prices, one should not rely on RAID alone to save the bacon. A RAID
system is not a substitute for a good backup regime. I speak from
experience and run RAID in all our servers
Raid Arrays can get corrupted (admittedly this is less common with RAID1
(mirroring)Arrays) but it can and does happen.
Multiple disk failures can occur, I had a High end Compaq Server which
had 3 drive failures almost at the same time. I was really lucky with
this one, it was RAID5 with 4 active drives and 2 hot spares. In this
setup one can only recover from one active drive failure at a time, in
my case I lost one active drive and the 2 spares.
With RAID5 Arrays one of the possible issues is the invisible and
partial failure of your spare(s) you only get to find out about this
when the spares are put under pressure rebuilding for a failed Active
drive.
Another tip is to avoid using a RAID setup where all drives are from the
same production batch since drives from the same batch are more likely
to share a manufacturing inconsistency and fail at the same time
Monitor the health of your drives, drives can start showing soft
(correctable ) errors long before they reach failure point however if
the other drive(s) that you are depending on to rebuild after outright
failure are showing soft errors the extra workload involved rebuilding
once the failed drive is replaced may be enough to cause the Drive to
fail before the job is done.
There are lots of utilities that can read S.M.A.R.T data from drives and
notify you when things start to change for the worse
In Summary, RAID is good but it is no substitute for a proper off line
backup regime, heck even a $25 USB stick is enough to hold your log &
reg key safe.
73
Brendan EI6IZ
