On 2015-08-26 07:50, Roman Mamedov wrote:
> On Wed, 26 Aug 2015 10:56:03 +0200
> George Duffield <forumscollective@gmail.com> wrote:
>
>> I'm looking to switch from a 5x3TB mdadm raid5 array to a Btrfs based
>> solution that will involve duplicating a data store on a second
>> machine for backup purposes (the machine is only powered up for
>> backups).
>
> What do you want to achieve by switching? As Btrfs RAID5/6 is not safe yet, do
> you also plan to migrate to RAID10, losing in storage efficiency?
>
> Why not use Btrfs in single-device mode on top of your mdadm RAID5/6? Can even
> migrate without moving any data if you currently use Ext4, as it can be
> converted to Btrfs in-place.
>
As of right now, btrfs-convert does not work reliably or safely.  I 
would strongly advise against using it unless you are trying to help get 
it working again.