8.04 md raid5 troubleshooting

[Reinhard Haller]

Am 09.11.2011 20:15, schrieb Marius Gedminas:
> On Wed, Nov 09, 2011 at 05:40:37PM +0100, Reinhard Haller wrote:
>>
>> Does it make sense to create a RAID-1 with the spare drive and the
>> "defective" drive to clone the boot partition (assuming the
>> defective drive is responsive)?
> Most disk failures I've seen are localized: you can't read the data from
> one particular bit.  It so happened that the bit that couldn't be read
> appeared in the middle of your RAID-5 partition (statistically likely,
> since RAID takes most up of the disk's sectors).  So, no, I wouldn't
> expect any issues accessing the old boot partition.
In the meantime the extended selftest finished without problems (the 
only significant difference between the defective drive and the others 
is a reallocated sector count of 1).
>
> RAID-1 sounds like a good idea.  I'm not exactly sure how you can
> convert an existing standalone partition into a RAID-1 array; you
> probably need to shrink it first a bit to leave space for the RAID
> metadata, which, I think, lives at the end?
Hope to find an Howto

Thanks
Reinhard