Re: Removing a failing drive from multiple arrays

[NeilBrown <neilb@suse.de>]

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On Sun, 22 Apr 2012 18:33:36 -0400 Bill Davidsen <davidsen@tmr.com> wrote:

> NeilBrown wrote:
> > On Thu, 19 Apr 2012 14:54:30 -0400 Bill Davidsen<davidsen@tmr.com>  wrote:
> >
> >> I have a failing drive, and partitions are in multiple arrays. I'm
> >> looking for the least painful and most reliable way to replace it. It's
> >> internal, I have a twin in an external box, and can create all the parts
> >> now and then swap the drive physically. The layout is complex, here's
> >> what blkdevtra tells me about this device, the full trace is attached.
> >>
> >> Block device sdd, logical device 8:48
> >> Model Family:     Seagate Barracuda 7200.10
> >> Device Model:     ST3750640AS
> >> Serial Number:    5QD330ZW
> >>       Device size   732.575 GB
> >>              sdd1     0.201 GB
> >>              sdd2     3.912 GB
> >>              sdd3    24.419 GB
> >>              sdd4     0.000 GB
> >>              sdd5    48.838 GB [md123] /mnt/workspace
> >>              sdd6     0.498 GB
> >>              sdd7    19.543 GB [md125]
> >>              sdd8    29.303 GB [md126]
> >>              sdd9   605.859 GB [md127] /exports/common
> >>     Unpartitioned     0.003 GB
> >>
> >> I think what I want to do is to partition the new drive, then one array
> >> at a time fail and remove the partition on the bad drive, and add a
> >> partition on the new good drive. Then repeat for each array until all
> >> are complete and on a new drive. Then I should be able to power off,
> >> remove the failed drive, put the good drive in the case, and the arrays
> >> should reassemble by UUID.
> >>
> >> Does that sound right? Is there an easier way?
> >>
> > I would add the new partition before failing the old but that isn't a big
> > issues.
> >
> > If you were running a really new kernel, used 1.x metadata, and were happy to
> > try out code that that hasn't had a lot of real-life testing you could (after
> > adding the new partition) do
> >     echo want_replacement>  /sys/block/md123/md/dev-sdd5/state
> > (for example).
> >
> > Then it would build the spare before failing the original.
> > You need linux 3.3 for this to have any chance of working.
> >
> > NeilBrown
> 
> I expect to try this in a real world case tomorrow. Am I so lucky that when 
> rebuilding the failing drive will be copies in a way which uses a recovered 
> value for the chunk if there's a bad block? And only if there's a bad block, so 
> that possible evil on the other drives would not be a problem unless they were 
> at the same chunk?

That's the theory, yes.

> 
> As soon as the pack of replacements arrives I'll let you know how well this 
> worked, if at all.
> 
> 

Thanks.

NeilBrown


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