Re: adding new devices to degraded raid1

[Goffredo Baroncelli <kreijack@libero.it>]

On 8/27/20 2:41 PM, Eric Wong wrote:
> I don't need to do it right away, but is it possible to add new
> devices to a degraded raid1?
> 
> One thing I might do in the future is replace a broken big drive
> with two small drives.  It may even be used to migrate to SSDs.
> 
> Since btrfs-replace only seems to do 1:1 replacements, and I
> needed to physically remove an existing broken device to make
> room for the replacements, could I do something like:
> 
> 	mount -o degraded /mnt/foo
> 	btrfs device add small1 small2 /mnt/foo
> 	btrfs device remove broken /mnt/foo
> 
> ?
> 

Instead of

  	btrfs device remove broken /mnt/foo

You should do

	btrfs device remove missing /mnt/foo

("missing" has to be write as is, it is a special term, see man page)

and

	btrfs balance start /mnt/foo


To redistribute the data to the disks.

Please before trying it, wait for other suggestions or confirmation from more expert dveloper about that

BR
G.Baroncelli

> Anyways, so far raid1 has been working great for me, but I have
> some devices nearing 70K Power_On_Hours according to SMART
> 
> Thanks.
> 


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