Re: Can't remove missing drive

[William Uther <willu.mailingLists@cse.unsw.edu.au>]

Hi,

  I was trying to remove a 'missing' drive from a raid1 setup.  It was suggested on this list that I update to HEAD.  I updated my kernel to Ubuntu-lts-2.6.37-2.9, which appears to have the latest BTRFS code in it.  I then tried to remove my missing drive again:

root@willvo:~# btrfs filesystem show
failed to read /dev/sr0
Label: none  uuid: f929c413-01c8-443f-b4f2-86f36702f519
	Total devices 3 FS bytes used 594.71GB
	devid    1 size 931.51GB used 604.00GB path /dev/sdb1
	devid    2 size 931.51GB used 604.00GB path /dev/sdc1
	*** Some devices missing

Btrfs v0.19-36-gcbc979b-dirty
root@willvo:~# btrfs device delete missing /data
root@willvo:~# tail -1 /var/log/syslog
Nov  6 13:36:29 willvo kernel: [ 1227.711276] btrfs: no missing devices found to remove
root@willvo:~# btrfs filesystem show
failed to read /dev/sr0
Label: none  uuid: f929c413-01c8-443f-b4f2-86f36702f519
	Total devices 3 FS bytes used 594.71GB
	devid    1 size 931.51GB used 604.00GB path /dev/sdb1
	devid    2 size 931.51GB used 604.00GB path /dev/sdc1
	*** Some devices missing

Btrfs v0.19-36-gcbc979b-dirty

This is already strange as 'btrfs device delete' cannot find the missing device that 'btrfs filesystem show' knows about.  But then things get really strange...

root@willvo:~# btrfs filesystem df /data
Data, RAID0: total=1.18TB, used=596.74GB
System: total=4.00MB, used=96.00KB
Metadata, RAID0: total=2.00GB, used=993.35MB

Why is my filesystem suddenly showing RAID0?  Note that the used space displayed still seems to suggest raid 1.  Unfortunately I didn't notice the raid0 label right away, and did:

root@willvo:~# btrfs filesystem balance /data
root@willvo:~# btrfs filesystem show
failed to read /dev/sr0
Label: none  uuid: f929c413-01c8-443f-b4f2-86f36702f519
	Total devices 3 FS bytes used 594.71GB
	devid    1 size 931.51GB used 298.88GB path /dev/sdb1
	devid    2 size 931.51GB used 298.88GB path /dev/sdc1
	*** Some devices missing

Btrfs v0.19-36-gcbc979b-dirty
root@willvo:~# btrfs filesystem df /data
Data, RAID0: total=596.00GB, used=593.75GB
System: total=4.00MB, used=52.00KB
Metadata, RAID0: total=1.75GB, used=979.95MB

Which seems to have believed the spurious raid0 setting and converted my setup from raid1 to raid0 - albeit still with missing devices.

Is there any way to 'convert back' to raid1?  My reading suggests that feature isn't implemented yet - although I managed to magically convert from raid1 to raid0, so who knows.

Cheers,

Will      :-}