Re: destroyed disk in btrfs raid

[laie <laie@halifax.rwth-aachen.de>]

On 2014-05-14 20:44, Hugo Mills wrote:
> On Wed, May 14, 2014 at 08:43:41PM +0200, laie wrote:
>> On 2014-05-11 16:19, Hugo Mills wrote:
>> >On Tue, May 13, 2014 at 10:16:59AM +0200, laie wrote:
>> >>On 2014-05-09 20:01, Hugo Mills wrote:
>> >>>On Fri, May 09, 2014 at 06:58:27PM +0100, Hugo Mills wrote:
>> >>>>On Fri, May 09, 2014 at 08:02:45PM +0200, laie wrote:
>> >>>>> Now I'm looking for a way to tell btrfs to provide me with a list of the
>> >>>>> corrupted files and delete them afterwards. This would be great, because
>> >>>>> otherwise it would take very long to get the data back from slow backups.
>> >>>>
>> >>>>   Simple solution: cat every file to /dev/null, and see which ones
>> >>>>fail with an I/O error. With RAID-0 data, losing a device is going to
>> >>>>damage most files, though, so don't necessarily expect much to survive.
>> 
>> I finished building the List, about 40% of the Data is gone. So far so 
>> good.
>> 
>> As next step I planned to delete these files. This is not possible 
>> because
>> I'm not able to mount the fs r/w.
>> 
>> btrfs: allowing degraded mounts
>> btrfs: bdev /dev/mapper/luks-0 errs: wr 37519, rd 32783, flush 0, 
>> corrupt 0,
>> gen 0
>> Btrfs: too many missing devices, writeable mount is not allowed
>> btrfs: open_ctree failed
>> 
>> Is it correct remove the missing device now:
>> 
>> btrfs device delete missing /mnt
>> 
>> Or do I have to add the replacement first?
> 
>    You'd have to mount r/w before you can add a new disk. :)
> 
>    You should be able to mount r/w using the -o degraded mount option.

The error above is occurs when I try to mount with

mount -o degraded source target

only

mount -o degraded,ro source target

works.