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* Hugo. [snip] -- Hugo Mills | UNIX: Japanese brand of food containers hugo@... carfax.org.uk | http://carfax.org.uk/ | PGP: E2AB1DE4 |
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