Re: How to handle a RAID5 arrawy with a failing drive?

ronnie sahlberg
2014-03-16T23:40:40Z

On Sun, Mar 16, 2014 at 4:17 PM, Marc MERLIN <marc@merlins.org> wrote:
> On Sun, Mar 16, 2014 at 05:12:10PM -0600, Chris Murphy wrote:
>>
>> On Mar 16, 2014, at 4:55 PM, Chris Murphy <lists@colorremedies.com> wrote:
>>
>> > Then use btrfs replace start.
>>
>> Looks like in 3.14rc6 replace isn't yet supported. I get "dev_replace cannot yet handle RAID5/RAID6".
>>
>> When I do:
>> btrfs device add <new> <mp>
>>
>> The command hangs, no kernel messages.
>
> Ok, that's kind of what I thought.
> So, for now, with raid5:
> - btrfs seems to handle a drive not working
> - you say I can mount with the drive missing in degraded mode (I haven't
> tried that, I will)
> - but no matter how I remove the faulty drive, there is no rebuild on a
> new drive procedure that works yet
>
> Correct?

There was a discussion a while back that suggested that a "balance"
would read all blocks and write them out again and that would recover
the data.

I have no idea if that works or not.
Only do this as a last resort once you have already considered all
data lost forever.