On Wed, 11 Apr 2012 19:10:47 -0700 (PDT) jahammonds prost <gmitch64@xxxxxxxxx> wrote: > > I think it is best to recover, and then reshape later. > > Which is what I did. The destructive badblocks ran fine overnight, with no errors on the drives that were failed out of the array. Interestingly one of the additional drives that I want to add took an additional 6 hours to run badblocks, so I need to look into that a bit. > > I am having a bit of an issue with the reshape tho... When I try and add one of the 2 additional devices I want to add (I'm going to add them one at a time), I get an error about the bitmap needing to be removed. > > mdadm --grow /dev/md0 --raid-devices=16 > mdadm: Need to backup 93184K of critical section.. > mdadm: Cannot set device shape for /dev/md0: Device or resource busy > Bitmap must be removed before shape can be changed > > Now, the docs (and indeed several websites when I googled) suggest that you can have a bitmap present on a grow, and the help suggests that you can even change it during a grow.. > > > If the word internal is given, then the bitmap is stored with the metadata on the array, and so is replicated on all devices. If the word none is given with --grow mode, then any bitmap that is present is removed. > > > Is there an issue with the array, or just in my understanding and google foo? You cannot reshape an array while it has a bitmap attached. This restriction will probably be removed in Linux 3.5 NeilBrown > > I am running on Centos 6 (2.6.32-220.7.1.el6.x86_64) with madam (mdadm - v3.2.2 - 17th June 2011) > > > Thanks again. > > > > > ----- Original Message ----- > From: NeilBrown <neilb@xxxxxxx> > To: jahammonds prost <gmitch64@xxxxxxxxx> > Cc: Linux RAID <linux-raid@xxxxxxxxxxxxxxx> > Sent: Wednesday, 11 April 2012, 0:43 > Subject: Re: Failed Array Rebuild advice Please > > On Tue, 10 Apr 2012 21:14:07 -0700 (PDT) jahammonds prost > <gmitch64@xxxxxxxxx> wrote: > > > One other question as the badblocks progresses. > > > > > It will then recovery both devices in parallel. > > > > How many additional devices can be done at the same time? I presume that I am going to have to replace the 2 failed devices before I try and grow the array by adding 3 additional drives? I so, how many additional drives can be rebuilt concurrently with a grow? Could I add 5 devices and not see too much of a performance hit? Or would it be more sensible to add them one at a time? > > > > I think it is best to recover, and then reshape later. I cannot promise that > doing them both at once will work .... it might but I have a feeling that > there might be problems. > > Adding three additional drives at once should work well enough in terms of > performance. > However I would only do it if I were very very confident of the drives. > If you hit bad blocks you start losing drives, and if you have 3 drives that > you haven't used before, the chance of losing them all during the reshape - > while still small - becomes a little too high for comfort. > > But if you have run heavy bad-blocks tests on them all and they appear to > work, then adding 3 drives at once should be fine. > > NeilBrown
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