I have a BTRFS volume with four devices one of which has not failed and is no longer present in the machine. The volume is mounted in degraded mode. I am trying to remove the failed device with: btrfs device remove missing /data There should be enough space to consolidate the data onto the three remaining disc before adding a fourth. The first few attempts have failed with errors of the form: Jun 12 14:54:36 meije kernel: BTRFS info (device sda): relocating block group 10436799889408 flags data|raid5 Jun 12 14:54:41 meije kernel: BTRFS warning (device sda): csum failed root -9 ino 272 off 519241728 csum 0x9cb8912f expected csum 0x73ba6e2a mirror 2 Jun 12 14:54:41 meije kernel: BTRFS warning (device sda): csum failed root -9 ino 272 off 519245824 csum 0x98f94189 expected csum 0x4ab823e6 mirror 2 Jun 12 14:54:41 meije kernel: BTRFS warning (device sda): csum failed root -9 ino 272 off 519254016 csum 0xd3f53909 expected csum 0x94ab4db4 mirror 2 Jun 12 14:54:41 meije kernel: BTRFS warning (device sda): csum failed root -9 ino 272 off 519249920 csum 0xcb29eade expected csum 0x65d28b9e mirror 2 Jun 12 14:54:41 meije kernel: BTRFS warning (device sda): csum failed root -9 ino 272 off 519258112 csum 0x714821f5 expected csum 0xeed771e2 mirror 2 Jun 12 14:54:41 meije kernel: BTRFS warning (device sda): csum failed root -9 ino 272 off 519262208 csum 0x574f1bdc expected csum 0x5a78e046 mirror 2 Jun 12 14:54:41 meije kernel: BTRFS warning (device sda): csum failed root -9 ino 272 off 519266304 csum 0x63ec8641 expected csum 0xcee67afe mirror 2 Jun 12 14:54:41 meije kernel: BTRFS warning (device sda): csum failed root -9 ino 272 off 519270400 csum 0xb3d8a215 expected csum 0x39db0f0a mirror 2 Jun 12 14:54:41 meije kernel: BTRFS warning (device sda): csum failed root -9 ino 272 off 519274496 csum 0x910dd641 expected csum 0x3599ad7d mirror 2 Jun 12 14:54:41 meije kernel: BTRFS warning (device sda): csum failed root -9 ino 272 off 519278592 csum 0xe6ca8bc2 expected csum 0x413d5da7 mirror 2 Deleting the files concerned allows it to progress further and the device remove has been logging messages of the form: Jun 13 21:14:01 meije kernel: BTRFS info (device sda): relocating block group 7956456275968 flags data|raid5 Jun 13 21:14:36 meije kernel: BTRFS info (device sda): found 785 extents Jun 13 21:14:46 meije kernel: BTRFS info (device sda): found 785 extents The numbers obviously vary but the pattern of those three lines which the block group and two identical "found extents" lines has been repeating for several hours and the amount of data reported by: btrfs fi usage /data as being on the missing disc has been gradually reducing and the amount on the other three gradually increasing just as I would expect. Now, however, there is a new pattern: Jun 13 21:14:54 meije kernel: BTRFS info (device sda): relocating block group 7955382534144 flags metadata|raid1 Jun 13 21:18:51 meije kernel: BTRFS info (device sda): found 51353 extents Jun 13 21:19:18 meije kernel: BTRFS info (device sda): found 1 extents Jun 13 21:19:23 meije kernel: BTRFS info (device sda): found 1 extents Jun 13 21:19:27 meije kernel: BTRFS info (device sda): found 1 extents Jun 13 21:19:32 meije kernel: BTRFS info (device sda): found 1 extents Jun 13 21:19:36 meije kernel: BTRFS info (device sda): found 1 extents Jun 13 21:19:40 meije kernel: BTRFS info (device sda): found 1 extents Jun 13 21:19:44 meije kernel: BTRFS info (device sda): found 1 extents Jun 13 21:19:48 meije kernel: BTRFS info (device sda): found 1 extents Jun 13 21:19:52 meije kernel: BTRFS info (device sda): found 1 extents With the last line repeating. So far there have been 9,347 of the "found 1 extents" messages with no other BTRFS messages in between. The amount of data on the missing disc does not seem to be decreasing now. Does this seem like normal behaviour, or has it not got stuck in an infinite loop, i.e. is it finding the same extent over and over again? What should I do? Regards, Steve.
