Re: replace disk in raid5 without linux noticing?

[Ming Zhang <mingz@ele.uri.edu>]

On Thu, 2006-04-20 at 17:22 +0200, Gabor Gombas wrote:
> On Wed, Apr 19, 2006 at 02:16:10PM -0400, Ming Zhang wrote:
> 
> > is this possible? 
> > * stop RAID5
> > * set a mirror between current disk X and a new added disk Y, and X as
> > primary one (which means copy X to Y to full sync, and before this ends,
> > only read from X); also this mirror will not have any metadata or mark
> > on existing disk;
> 
> The mirror should be created without persistent superblocks (obviously),
> but --build does not seem to allow RAID1.
> 
> > * add this mirror to RAID5
> > * start RAID5;
> > 
> > ... mirror will continue copy data from X to Y, once end
> > 
> > * stop RAID5
> > * split mirror
> > * put DISK Y back to RAID5
> > * restart RAID5.
> > 
> > since this is a mirror, all metadata are same. it will be even greater
> > if no need to stop raid5 to do this.
> 
> The process seems rather fragile. If I created a RAID5 array to protect
> my data I most certainly would not like to perform so much steps where I
> can mess up.

it can be be script and then little chance to get failed.


or if i understand current raid5 bitmap right. u can remove the disk X
from raid, then do a dd from disk X to Y, and then add disk Y to raid.
then bitmap can handle the rsync with a much less cost.




> 
> Gabor
>