> dd that backup disk to another disk, so you have a backup of your > backup, and work with that. OK. > You can also post the dmesg output you get when you mount the broken > filesystem, and ask the experts if it might be worth to try experimental > btrfs.fsck on it. dmesg does not output anything of value since the file system is not detectable, here is the kernel output: [ 4834.149123] usb 2-1.1: new high speed USB device number 12 using ehci_hcd [ 4834.245114] scsi20 : usb-storage 2-1.1:1.0 [ 4835.246193] scsi 20:0:0:0: Direct-Access WDC WD75 00BPVT-22HXZT1 1A01 PQ: 0 ANSI: 2 CCS [ 4835.317195] sd 20:0:0:0: Attached scsi generic sg4 type 0 [ 4835.317889] sd 20:0:0:0: [sdc] 1465149168 512-byte logical blocks: (750 GB/698 GiB) [ 4835.318944] sd 20:0:0:0: [sdc] Write Protect is off [ 4835.318956] sd 20:0:0:0: [sdc] Mode Sense: 00 38 00 00 [ 4835.320603] sd 20:0:0:0: [sdc] Asking for cache data failed [ 4835.320619] sd 20:0:0:0: [sdc] Assuming drive cache: write through [ 4835.324143] sd 20:0:0:0: [sdc] Asking for cache data failed [ 4835.324153] sd 20:0:0:0: [sdc] Assuming drive cache: write through [ 4836.894263] sdc: sdc1 [ 4836.897190] sd 20:0:0:0: [sdc] Asking for cache data failed [ 4836.897200] sd 20:0:0:0: [sdc] Assuming drive cache: write through [ 4836.897206] sd 20:0:0:0: [sdc] Attached SCSI disk [ 4844.803652] EXT3-fs (dm-1): error: can't find ext3 filesystem on dev dm-1. [ 4844.856054] EXT2-fs (dm-1): error: can't find an ext2 filesystem on dev dm-1. [ 4844.902679] EXT4-fs (dm-1): VFS: Can't find ext4 filesystem [ 4932.637108] EXT3-fs (dm-1): error: can't find ext3 filesystem on dev dm-1. [ 4932.686841] EXT2-fs (dm-1): error: can't find an ext2 filesystem on dev dm-1. [ 4932.738999] EXT4-fs (dm-1): VFS: Can't find ext4 filesystem [ 4949.142867] EXT3-fs (dm-1): error: can't find ext3 filesystem on dev dm-1. [ 4949.197596] EXT2-fs (dm-1): error: can't find an ext2 filesystem on dev dm-1. [ 4949.241721] EXT4-fs (dm-1): VFS: Can't find ext4 filesystem > fwiw, I backup to gpg encrypted files stored on ext4 to cope with > regressions in both btrfs and disk encryption. In my experience btrfs + encryption eats the data, this is not the first time I had this problem with btrfs so I am considering switching to ext4, but can I still get the other data back on the broken btrfs?? -- Thanks -- 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
