Hi Chris,
thanks for your reply.
>> ./btrfs filesystem show /dev/sdb1
Label: none uuid: 989306aa-d291-4752-8477-0baf94f8c42f
Total devices 2 FS bytes used 3.47TiB
devid 1 size 2.73TiB used 1.74TiB path /dev/sdb1
devid 2 size 2.73TiB used 1.74TiB path /dev/sdc1
I don't understand the no spare part. You have 3.47T of data, and yet the
single device size is 2.73T.
There is no way to migrate 1.74T from sdc1 to sdb1 because there isn't enough
space.
Fair point. I summed up manually (with du) and apparently missed some
data. I can move the 0.8TiB out of the way. I just don't have 3.5TiB
'spare'.
btrfs device delete /dev/sdc1 /mnt/BTRFS/rsnapshot/
btrfs device delete /dev/sdc1 /mnt/BTRFS/backups/
btrfs device delete /dev/sdc1 /mnt/BTRFS/Video/
btrfs filesystem balance start /mnt/BTRFS/Video/
I don't understand this sequence because I don't know what you've mounted where,
I'm sorry. here you go:
/btrfs subvolume list /mnt/BTRFS/Video
ID 256 gen 226429 top level 5 path Video --> /mnt/BTRFS/Video/
ID 1495 gen 226141 top level 5 path rsnapshot --> /mnt/BTRFS/rsnapshot
ID 4444 gen 226429 top level 256 path Snapshot --> not mounted
ID 5845 gen 226375 top level 5 path backups --> /mnt/BTRFS/backups
but in any case maybe it's a bug that you're not getting errors for each
> of these commands because you can't delete sdc1 from a raid0 volume.
That makes sense. I read that procedure somewhere in the -totally
unvalidated- Internet.
In case the missing Error-Message is a Bug: Is this place here
sufficient to report it, or is there a Bug-Tracker?
> You'd first have to convert the data, metadata, and system profiles to
> single (metadata can be set to dup). And then you'd be able to delete
> a device so long as there's room on remaining devices, which you
don't have.
Yes, but I can create that space.
So, for me the next steps would be to:
-generate enough room on the filesystem
-btrfs balance start -dconvert=raid1 -mconvert=raid1 /mnt/BTRFS/Video
-btrfs device delete /dev/sdc1 /mnt/BTRFS/Video
Right?
next, I'm doing the balance for the subvolume /mnt/BTRFS/backups
You told us above you deleted that subvolume. So how are you balancing it?
Yes, that was my understanding from my research:
You tell btrfs, that you want to remove one disc from the filesystem and
then balance it to move the data on the remaining disc. I did find this
logical. I was expecting that I possibly need a further command to tell
btrfs that it's not a raid anymore, but I thought this could also be
automagical.
I understand, that's not the way it is implemented, but it's not a crazy
idea, is it?
And also, balance applies to a mountpoint, and even if you mount a
> subvolume to that mountpoint, the whole file system is balanced.
> Not just the mounted subvolume.
That is confusing. (I mean: I understand what you are saying, but it's
counterintuitive). Why is this the case?
In parallel, I try to delete /mnt/BTRFS/rsnapshot, but it fails:
btrfs subvolume delete /mnt/BTRFS/rsnapshot/
Delete subvolume '/mnt/BTRFS/rsnapshot'
ERROR: cannot delete '/mnt/BTRFS/rsnapshot' - Inappropriate ioctl
for device
Why's that?
But even more: How do I free sdc1 now?!
Well I'm pretty confused because again, I can't tell if your paths refer to
> subvolumes or if they refer to mount points.
Now I am confused. These paths are the paths to which I mounted the
subvolumes:
my (abbreviated) fstab:
UUID=xy /mnt/BTRFS/Video btrfs subvol=Video
UUID=xy /mnt/BTRFS/rsnapshot btrfs subvol=rsnapshot
UUID=xy /mnt/BTRFS/backups btrfs subvol=backups
> The balance and device delete commands all refer to a mount point,
which is the path returned by the df command.
So this:
/dev/sdb1 5,5T 3,5T 2,0T 64% /mnt/BTRFS/Video
/dev/sdb1 5,5T 3,5T 2,0T 64% /mnt/BTRFS/backups
/dev/sdc1 5,5T 3,5T 2,0T 64% /mnt/BTRFS/rsnapshot
The subvolume delete command needs a path to subvolume that starts with the
mount point.
Sorry, this I do not understand, no matter how hard I think about it..
What would it be in my case?
Thanks for your help! I appreciate it.
Greetings,
Hendrik
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