On Mon, Oct 08, 2018 at 11:01:35PM +0200, Pierre Couderc wrote: > On 10/08/2018 06:14 PM, Hugo Mills wrote: > >On Mon, Oct 08, 2018 at 04:10:55PM +0000, Hugo Mills wrote: > >>On Mon, Oct 08, 2018 at 03:49:53PM +0200, Pierre Couderc wrote: > >>>I ma trying to make a "RAID1" with /dev/sda2 ans /dev/sdb (or similar). > >>> > >>>But I have stranges status or errors about "missing devices" and I > >>>do not understand the current situation : > >>> > >>> > >>>root@server:~# btrfs fi show > >>>Label: none uuid: 28c2b7ab-631c-40a3-bab7-00dac5dd20eb > >>> Total devices 1 FS bytes used 190.91GiB > >>> devid 1 size 1.82TiB used 196.02GiB path /dev/sda2 > >>> > >>>warning, device 1 is missing > >>>Label: none uuid: 2d45149a-fb97-4c2a-bae2-4cfe4e01a8aa > >>> Total devices 2 FS bytes used 116.18GiB > >>> devid 2 size 1.82TiB used 118.03GiB path /dev/sdb > >>> *** Some devices missing > >> This looks like you've created a RAID-1 array with /dev/sda2 and > >>/dev/sdb, and then run mkfs.btrfs again on /dev/sda2, overwriting the > >>original [part of a] filesystem on /dev/sda2, and replacing it with a > >>wholly different filesystem. Since the new FS on /dev/sda2 (UUID > >>28c2...) doesn't have the same UUID as the original FS (UUID 2d45...), > >>and the original FS was made of two devices, btrfs fi show is telling > >>you that there's some devices missing -- /dev/sda2 is no longer part > >>of that FS, and is therefore a missing device. > >> > >> I note that you've got data on both filesystems, so they must both > >>have been mounted somewhere and had stuff put on them. > >> > >> I recommend doing something like this: > >> > >># mkfs /media/btrfs/myraid1 /media/btrfs/tmp > >># mount /dev/sdb /media/btrfs/myraid1/ > >># mount /dev/sda2 /media/btrfs/tmp/ # mount both filesystems > >># cp /media/btrfs/tmp/* /media/btrfs/myraid1 # put it where you want it > >># umount /media/btrfs/tmp/ > >># wipefs /dev/sda2 # destroy the FS on sda2 > >># btrfs replace start 1 /dev/sda2 /media/btrfs/myraid1/ > >> > >> This will copy all the data from the filesystem on /dev/sda2 into > >>the filesystem on /dev/sdb, destroy the FS on sda2, and then use sda2 > >>as the second device for the main FS. > >> > >>*WARNING!* > >> > >> Note that, since the main FS is missing a device, it will probably > >>need to be mounted in degraded mode (-o degraded), and that on kernels > >>earlier than (IIRC) 4.14, this can only be done *once* without the FS > >>becoming more or less permanently read-only. On recent kernels, it > >>_should_ be OK. > >> > >>*WARNING ENDS* > > Oh, and for the record, to make a RAID-1 filesystem from scratch, > >you simply need this: > > > ># mkfs.btrfs -m raid1 -d raid1 /dev/sda2 /dev/sdb > > > > You do not need to run mkfs.btrfs on each device separately. > > > > Hugo. > Thnk you very much. I understand a bit better. I think that I have > nothing of interest on /dev/sdb and that its contents is the result > of previous trials. > And that my system is on /dev/dsda2 as : > > root@server:~# df -h > Filesystem Size Used Avail Use% Mounted on > udev 3.9G 0 3.9G 0% /dev > tmpfs 787M 8.8M 778M 2% /run > /dev/sda2 1.9T 193G 1.7T 11% / > tmpfs 3.9G 0 3.9G 0% /dev/shm > tmpfs 5.0M 0 5.0M 0% /run/lock > tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup > /dev/sda1 511M 5.7M 506M 2% /boot/efi > tmpfs 100K 0 100K 0% /var/lib/lxd/shmounts > tmpfs 100K 0 100K 0% /var/lib/lxd/devlxd > root@server:~# > > Is it exact ?
Yes, it looks like you're running / from the FS on /dev/sda2. > If yes, I suppose I should wipe data on /dev/sdb, then build the > RAID by expanding /dev/sda2. Correct. I would recommend putting a partition table on /dev/sdb, because it doesn't take up much space, and it's always easier to have one already there when you need it (and there's a few things that can get confused if there isn't a partition table). > So I should : > > wipefs /dev/sdb > btrfs device add /dev/sdb / > btrfs balance start -v -mconvert=raid1 -dconvert=raid1 / > Does it sound correct ? (my kernel is boot/vmlinuz-4.18.0-1-amd64) Yes, exactly. Hugo. -- Hugo Mills | Yes, this is an example of something that becomes hugo@... carfax.org.uk | less explosive as a one-to-one cocrystal with TNT. http://carfax.org.uk/ | (Hexanitrohexaazaisowurtzitane) PGP: E2AB1DE4 | Derek Lowe
signature.asc
Description: Digital signature
