[linux-lvm] Mirror resync direction

[Paul LeoNerd Evans]

On Thu, 26 Oct 2006 16:14:34 -0500
Jonathan E Brassow <jbrassow at redhat.com> wrote:

> This doesn't really reflect what would happen if you replaced a disk, I 
> don't think.  With this, you are simply going around mirror's back to 
> write data to a device which it controls.

Well, I did it with the VG turned off; namely

  vgchange -a n

> In real life, I think you would have a disk failure (which would force 
> you to run 'vgreduce --removemissing vg'), then you would insert a new 
> block device, pvcreate/vgextend/lvconvert.

Yes, I wasn't aware of that procedure before, but Alasdair Kergon's mail
has pointed that out to me - I've tried with that and it seems to work
fine.

> LVM2 mirroring is still a work in progress (trying to get the right 
> pieces upstream).  Depending on the version of LVM2 and the kernel 
> patches you have, it may not work.

Seems happy once I follow the correct procedure - see above :)

> The use of --corelog simply means that the mirror device will be 
> resynchronized every time the device is activated.  The persistent log 
> (disk log) tracks what resynchronization has been done and can avoid 
> all complete resyncs.

Yes, I'm aware of that bit, but I couldn't see any other way to achieve
it with only two PVs. The "--alloc anywhere" as suggested in the error
message doesn't have any effect for me.

-- 
Paul "LeoNerd" Evans

leonerd at leonerd.org.uk
ICQ# 4135350       |  Registered Linux# 179460
http://www.leonerd.org.uk/
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