--- Austin Franklin <darkroom@ix.netcom.com> wrote:
> > I just wanted to note that RAID 0 is, in most cases, a bad idea.
> > The reason
> > is that if you stripe your data across multiple disks and one
> fails, you
> > lose all the data. It's better to split the files up among many,
> smaller
> > logical drives. It's great from a performance standpoint but
> that's about
> > it. RAID 0+1 or RAID 5 are much better ideas.
> >
> > Paul Wilson
>
> I disagree that it's a bad idea. It's no more "unsafe" than a single
> disk.
> MTBF is NOT additive. RAID 0 IS the fastest, and if that's what you
> need,
> then it's a good idea.
It *IS* more unsafe to use RAID0. And MTBF *IS* additive. Actually,
more exactly it is reduced and not increased. If you have 1 drive with
a MTBF of 100000 hours you can expect an error every 100000 hours in
average. If you have 4 drives each with an MTBF of 100000 then your
MTBF of your RAID0 system is 100000/4=25000 hours, i.e. in your RAID0
system an error will occur every 25000 hours in average and such an
error will be disasterous for the whole RAID0 sytem.
The abve does not take into account failures due to over-surge,
earthquakes, etc in which case MTBF is not linear. But MTBF for an
individual HD does not take these kind of events into account either.
Anyway, 25000 hours is almost 3 years. Taking into account that with
most home systems you don't use more then 2 drives, that with many
solutions you don't gain much speed with more then 2 drives, and that
the MTBF can be considerable higher a failure is even much more
unlikely. Therefore, with some backup, RAID 0 is still a good solution
if you want to have higher speed. This is especially true if you work
with big files. 50 MBytes image files already take quite a while to
store an a regular system. When you work with files that have multiple
100 MBytes then a RAID0 system is sure quite helpful.
Robert
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