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Re: LVM big problem



Luc MAIGNAN <luc maignan winxpert com> writes:
> I've setup a LVM volume on several disks.  It appears that one at
> least of the disks has crashed.  Is there a way to recover data on
> the good disks or all is lost ?

>From your backups?  (Sorry! Been there, felt your pain.)

A few years ago I once foolishly had 3 of Seagate's largest disks at
the time combined into a single logical volume spanning the volume
group.  The same thing happened to me.  One disk died leaving me with
1/3 of my data blocks missing in action.  Not much one can do.  It
isn't like having one or two bad blocks on a disk where the filesystem
is mostly ok.  Here 1/3 of everything is missing.

It was a good lesson to me as to why LVM across multiple disks is a
bad idea.  The overall reliability rate is the product of each of the
reliability rates.  If the disk is 95% reliable (5% failure rate) you
end up with (* 0.95 0.95 0.95) 0.857 (or roughly 86% overall
reliability).  As it turns out the Seagate 200GB and 250GB SATA's I
had both had a 50% failure rate in 2 years.

-wolfgang
-- 
Wolfgang S. Rupprecht              http://www.full-steam.org/  (ipv6-only)
         You may need to config 6to4 to see the above pages.


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