Re: A partially failing disk in raid0 needs replacement

[Roman Mamedov <rm@romanrm.net>]

On Tue, 14 Nov 2017 10:36:22 +0200
Klaus Agnoletti <klaus@agnoletti.dk> wrote:

> Obviously, I want /dev/sdd emptied and deleted from the raid.

  * Unmount the RAID0 FS

  * copy the bad drive using `dd_rescue`[1] into a file on the 6TB drive
    (noting how much of it is actually unreadable -- chances are it's mostly
    intact)

  * physically remove the bad drive (have a powerdown or reboot for this to be
    sure Btrfs didn't remember it somewhere)

  * set up a loop device from the dd_rescue'd 2TB file

  * run `btrfs device scan`

  * mount the RAID0 filesystem

  * run the delete command on the loop device, it will not encounter I/O
    errors anymore.


[1] Note that "ddrescue" and "dd_rescue" are two different programs for the
same purpose, one may work better than the other. I don't remember which. :)

-- 
With respect,
Roman