Re: RAID1 to 10 (Synology NAS)

[NeilBrown <neilb@suse.de>]

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On Sun, 7 Apr 2013 09:54:20 +1200 Al Grant <bigal.nz@gmail.com> wrote:

> Hello,
> 
> I have a Synology NAS with two 3Tb disks in RAID1 (sda+sdb).
> 
> The output of /proc/mdstat is:
> 
> Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
> md2 : active raid1 sda3[0] sdb3[1]
>       2925544256 blocks super 1.2 [2/2] [UU]
> 
> md1 : active raid1 sdb2[1] sda2[0]
>       2097088 blocks [10/2] [UU________]
> 
> md0 : active raid1 sdb1[1] sda1[0]
>       2490176 blocks [10/2] [UU________]
> 
> unused devices: <none>
> 
> I have added another two 3Tb disks (sdc and sdd).
> 
> I would like if possible to convert the raid1 to raid10.
> 
> I have seen guides on google on how to do this either by:
> 
> Creating a RAID10 with the two new disks and specifying two disks as
> missing. Remove one old disk, sync and then add the fourth and final
> disk; OR
> 
> Another method outlined here:
> http://www.linuxquestions.org/questions/linux-server-73/convert-raid-1-system-into-raid-1-0-a-557471/

I would:
  Create a raid10 with the 2 new devices and alternating missing devices:
    mdadm -C  /dev/md3 -l10 -n4 /dev/sdc3 missing /dev/sdd3 missing

  copy data from /dev/md2 to /dev/md3 however you like.

  Confirm that you can see the new array after a reboot.

  Stop the old md2 and add the devices to md3
    mdadm -S /dev/md2
    mdadm /dev/md3 --add /dev/sdc3 /dev/sdd3

> 
> My issue is that I actually have md0 md1 and md2 (presumably because
> there are partitions which hold the OS for the NAS).

They should not interfere at all.  If probably make sense to partition the
new devices the same as the old devices, and add sdc2 and sdd2 to md1, and add
sdc1 and sdd1 to md2.  They have clearly been created in a way that makes it
easy to add extra  partitions when extra devices are added to the box.

NeilBrown


> 
> Can I still do this grow operation?
> 
> Is anyone able to help me through this please?
> 
> Thanks in advance
> 
> 
> --
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> - Clint Eastwood
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