Hi everybody, I could need some advice on recovering a sort of broken filesystem (power cycle death). It seems the first superblock is damaged, but I'm unable to recover from a good one.
Running on a livecd with latest kernel and btrfs-tools I could get my hands on, this is all the info I can give: # uname -a Linux archiso 4.4.1-2-ARCH #1 SMP PREEMPT Wed Feb 3 13:12:33 UTC 2016 x86_64 GNU/Linux # btrfs version btrfs-progs v4.5 # fdisk -l /dev/sda Disk /dev/sda: 119.2 GiB, 128035676160 bytes, 250069680 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: gpt Disk identifier: 8A4EA6CE-3E19-48DC-B6D3-A01F22F6EEC3 Device Start End Sectors Size Type /dev/sda1 2048 6143 4096 2M BIOS boot /dev/sda2 6144 250069646 250063503 119.2G Linux filesystem # btrfs-show-super -a /dev/sda2 superblock: bytenr=65536, device=/dev/sda2 --------------------------------------------------------- ERROR: bad magic on superblock on /dev/sda2 at 65536 superblock: bytenr=67108864, device=/dev/sda2 --------------------------------------------------------- csum 0xaf86e706 [match] bytenr 67108864 flags 0x1 ( WRITTEN ) magic _BHRfS_M [match] fsid 4fe9d531-bef6-431d-b6be-ed68df8023bc label generation 1176204 root 42795008 sys_array_size 226 chunk_root_generation 158914 root_level 1 chunk_root 20971520 chunk_root_level 0 log_root 0 log_root_transid 0 log_root_level 0 total_bytes 128032509952 bytes_used 79141912576 sectorsize 4096 nodesize 16384 leafsize 16384 stripesize 4096 root_dir 6 num_devices 1 compat_flags 0x0 compat_ro_flags 0x0 incompat_flags 0x69 ( MIXED_BACKREF | COMPRESS_LZO | BIG_METADATA | EXTENDED_IREF ) csum_type 0 csum_size 4 cache_generation 1176204 uuid_tree_generation 1176204 dev_item.uuid e0474a00-70fe-4aee-9dc4-467966f4998c dev_item.fsid 4fe9d531-bef6-431d-b6be-ed68df8023bc [match] dev_item.type 0 dev_item.total_bytes 128032509952 dev_item.bytes_used 128032505856 dev_item.io_align 4096 dev_item.io_width 4096 dev_item.sector_size 4096 dev_item.devid 1 dev_item.dev_group 0 dev_item.seek_speed 0 dev_item.bandwidth 0 dev_item.generation 0 To my understanding, that backup superblock looks healthy (I might be wrong though, just looking at the csum MATCH). So trying to recover from it: # btrfs check -s1 /dev/sda2 using SB copy 1, bytenr 67108864 checksum verify failed on 42795008 found 8FF848E2 wanted FFFFFFFF checksum verify failed on 42795008 found 8FF848E2 wanted FFFFFFFF checksum verify failed on 42795008 found 8FF848E2 wanted FFFFFFFF checksum verify failed on 42795008 found 8FF848E2 wanted FFFFFFFF bytenr mismatch, want=42795008, have=18446744073709551615 Couldn't read tree root Couldn't open file system # btrfs rescue super-recover -v /dev/sda2 All Devices: Device: id = 1, name = /dev/sda2 ctree.h:2068: btrfs_super_csum_size: Assertion `t >= ARRAY_SIZE(btrfs_csum_sizes)` failed. btrfs[0x436f6a] btrfs(btrfs_recover_superblocks+0x19c)[0x43712c] btrfs(main+0x82)[0x40adf2] /usr/lib/libc.so.6(__libc_start_main+0xf0)[0x7fd0ce8fa710] btrfs(_start+0x29)[0x40aef9] # btrfs-select-super -s1 /dev/sda2 checksum verify failed on 42795008 found 8FF848E2 wanted FFFFFFFF checksum verify failed on 42795008 found 8FF848E2 wanted FFFFFFFF checksum verify failed on 42795008 found 8FF848E2 wanted FFFFFFFF checksum verify failed on 42795008 found 8FF848E2 wanted FFFFFFFF bytenr mismatch, want=42795008, have=18446744073709551615 Couldn't read tree root Open ctree failed Trying to get the data off using restore, no surprise: # btrfs restore -u1 -D /dev/sda2 /mnt checksum verify failed on 42795008 found 8FF848E2 wanted FFFFFFFF checksum verify failed on 42795008 found 8FF848E2 wanted FFFFFFFF checksum verify failed on 42795008 found 8FF848E2 wanted FFFFFFFF checksum verify failed on 42795008 found 8FF848E2 wanted FFFFFFFF bytenr mismatch, want=42795008, have=18446744073709551615 Couldn't read tree root Could not open root, trying backup super Superblock bytenr is larger than device size Could not open root, trying backup super Do you have any advice on how to proceed here? Best regards, Thomas -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
