On Thu, 31 Aug 2017 07:45:55 -0400 "Austin S. Hemmelgarn" <ahferroin7@xxxxxxxxx> wrote: > If you use dm-cache (what LVM uses), you need to be _VERY_ careful and > can't use it safely at all with multi-device volumes because it leaves > the underlying block device exposed. It locks the underlying device so it can't be seen by Btrfs and cause problems. # btrfs dev scan Scanning for Btrfs filesystems # btrfs fi show Label: none uuid: 62ff7619-8202-47f6-8c7e-cef6f082530e Total devices 1 FS bytes used 112.00KiB devid 1 size 16.00GiB used 2.02GiB path /dev/mapper/vg-OriginLV # ls -la /dev/mapper/ total 0 drwxr-xr-x 2 root root 140 Aug 31 12:01 . drwxr-xr-x 16 root root 2980 Aug 31 12:01 .. crw------- 1 root root 10, 236 Aug 31 11:59 control lrwxrwxrwx 1 root root 7 Aug 31 12:01 vg-CacheDataLV_cdata -> ../dm-1 lrwxrwxrwx 1 root root 7 Aug 31 12:01 vg-CacheDataLV_cmeta -> ../dm-2 lrwxrwxrwx 1 root root 7 Aug 31 12:06 vg-OriginLV -> ../dm-0 lrwxrwxrwx 1 root root 7 Aug 31 12:01 vg-OriginLV_corig -> ../dm-3 # btrfs dev scan /dev/dm-0 Scanning for Btrfs filesystems in '/dev/mapper/vg-OriginLV' # btrfs dev scan /dev/dm-3 Scanning for Btrfs filesystems in '/dev/mapper/vg-OriginLV_corig' ERROR: device scan failed on '/dev/mapper/vg-OriginLV_corig': Device or resource busy -- With respect, Roman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
