Re: Converting from Raid 5 to 6

[NeilBrown <neilb@suse.de>]

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On Mon, 24 Oct 2011 21:19:22 +0100 Michael Busby <michael.a.busby@gmail.com>
wrote:

> Ok thanks, i have 1 small issue, when added the extra disk its been
> maked as spare, is this normal?
> 
> Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5]
> [raid4] [raid10]
> md0 : active raid6 sde[0] sdg[6](S) sda[4] sdb[3] sdd[2] sdc[1]
>       7814055936 blocks super 1.0 level 6, 512k chunk, algorithm 18
> [6/5] [UUUUU_]
>       [>....................]  reshape =  3.0% (59244544/1953513984)
> finish=11122.8min speed=2837K/sec
> 

It looks like the extra drive was added after you started the grow.

So it is still a spare.
Once the grow finishes you will have a singly-degraded RAID6.
Then it will immediately start recovering the missing device to the spare.

Did you add the extra drive after starting the grow - or before??

NeilBrown



> 
> 
> 
> On 24 October 2011 21:14, NeilBrown <neilb@suse.de> wrote:
> > On Mon, 24 Oct 2011 17:03:46 +0100 Michael Busby <michael.a.busby@gmail.com>
> > wrote:
> >
> >> should the speed be very slow when doing this progress, its a lot
> >> slower than a normal grow
> >
> > Yes.
> > The array is being reshaped in-place.  i.e. data is being read from part of
> > the array, rearranged, and written back to the same part of the array.
> > As you can imagine, this is risky - a crash will leave an inconsistent state.
> > Hence the backup file.  Everything in the array is first written to the
> > backup file, then back to the array.  So it is slow.
> >
> > A "normal" grow is writing to somewhere where there is no valid data, so it
> > doesn't need the backup.
> >
> > I do have a plan to make this faster.... but I have lots of plans and little
> > time.
> >
> > NeilBrown
> >
> >
> >
> >
> >>
> >> reshape =  1.2% (25006080/1953513984) finish=12481.8min speed=2574K/sec
> >>
> >> On 24 October 2011 15:11, Mathias Burén <mathias.buren@gmail.com> wrote:
> >> > On 24 October 2011 14:11, Michael Busby <michael.a.busby@gmail.com> wrote:
> >> >> At the moment i have a raid5 setup with 5 disks, i am looking to add a
> >> >> 6th disk and change from raid 5 to raid 6
> >> >>
> >> >> having looked at Neil's site i have found the following command, and
> >> >> just want to double check this is still the recommend way of
> >> >> converting
> >> >>
> >> >> mdadm --grow /dev/md0 --level=6 --raid-disks=6 --backup-file=/home/md.backup
> >> >>
> >> >> also would i need to add the extra disk before or after the command?
> >> >>
> >> >> cheers
> >> >> --
> >> >> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> >> >> the body of a message to majordomo@vger.kernel.org
> >> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >> >>
> >> >
> >> > Hi,
> >> >
> >> > I grew my 6 disk RAID5 to a 7 disk RAID6. First, add the drive. Then
> >> > partition it as required. Then add the drive to the array (I think
> >> > it'll become a spare?). Then you can grow it.
> >> >
> >> > Make sure you're using the latest mdadm tools available.
> >> >
> >> > Regards,
> >> > Mathias
> >> >
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> >> the body of a message to majordomo@vger.kernel.org
> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
> >


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