Re: unable to recover RAID 5 due to bad block

[NeilBrown <neilb@suse.de>]

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On Thu, 10 Nov 2011 12:50:46 -0400 Chris Purves <chris@northfolk.ca> wrote:

> On 2011-11-10 12:20, Alexander Kühn wrote:
> > ddrescue to the rescue!
> > Get a another new disk, then ddrescue the one with the read error to the new disk.
> > Assemble the array using the new disk instead of the one with the read error.
> > You will loose the blocks that can't be read of course.
> > And in the future do run raid check/scrubbing at regular intervals. ;)
> 
> I have tried this already.  After cloning the disk with errors, I replaced it with the clone and tried to re-start the array using
> 
> mdadm --assemble --force /dev/md1
> 
> mdadm assigned the new disk as a spare and said there were only three disks to start the array and so couldn't start it.
> 
> After I clone the disk with the error, how precisely should I re-start the array?
> 
> 

This should have worked.  So presumably some unstated requirement wasn't met.

Give details.  Names of devices, sizes of devices, "mdadm --examine" of
device.  Are you using partitions or whole disk ....

The best assemble command would be:
  mdadm --assemble /dev/md1 -vv ...list...of.devices..you...want.it.to.include. 


NeilBrown

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