Re: recovery problem raid5

[Hugo Mills <hugo@carfax.org.uk>]

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   The main thing you haven't tried here is mount -o degraded, which
is the thing to do if you have a missing device in your array.

   Also, that kernel's not really all that good for a parity RAID
array -- it's the very first one that had the scrub and replace
implementation, so it's rather less stable with parity RAID than the
later 4.x kernels. That's probably not the issue here, though.

   Hugo.

On Fri, Mar 18, 2016 at 06:41:32PM +0100, Marcin Solecki wrote:
> Hello all,
> I give up for this problem at restore my data
> 
> 
> # uname -a
> Linux jarvis.home 4.5.0-1.el7.elrepo.x86_64
> 
> # btrfs --version
> btrfs-progs v3.19.1
> 
> # btrfs fi show
> warning, device 4 is missing
> bytenr mismatch, want=21020672, have=21217280
> Couldn't read chunk root
> Label: none  uuid: 27ef2638-b50a-4243-80ed-40c3733ec11d
>         Total devices 4 FS bytes used 2.50TiB
>         devid    1 size 931.51GiB used 899.71GiB path /dev/sdd
>         devid    2 size 931.51GiB used 899.69GiB path /dev/sdb
>         devid    3 size 931.51GiB used 899.69GiB path /dev/sdc
>         *** Some devices missing
> 
> # mount  -o recovery /dev/sda /srv/
> mount: wrong fs type, bad option, bad superblock on /dev/sda,
>        missing codepage or helper program, or other error
> 
>        In some cases useful info is found in syslog - try
>        dmesg | tail or so.
> 
> dmesg after :
> [ 4886.521315] BTRFS info (device sdc): enabling auto recovery
> [ 4886.521320] BTRFS info (device sdc): disk space caching is enabled
> [ 4886.522853] BTRFS: failed to read chunk tree on sdc
> [ 4886.528789] BTRFS: open_ctree failed
> 
> #btrfs check --repair /dev/sda
> enabling repair mode
> warning, device 4 is missing
> bytenr mismatch, want=21020672, have=21217280
> Couldn't read chunk root
> Couldn't open file system
> 
> # btrfs rescue chunk-recover -v /dev/sda
> All Devices:
>         Device: id = 3, name = /dev/sdc
>         Device: id = 2, name = /dev/sdb
>         Device: id = 1, name = /dev/sda
> 
> [ 5164.468272] btrfs[3653]: segfault at 7f454014172e ip
> 0000000000423479 sp 00007f4482cec880 error 4 in btrfs[400000+83000]
> [ 5168.928317] btrfs[3657]: segfault at 7fd18c14172e ip
> 0000000000423479 sp 00007fd0d5858880 error 4 in btrfs[400000+83000]
> [ 5173.812457] btrfs[3662]: segfault at 7fd76c14172e ip
> 0000000000423479 sp 00007fd6b0e59880 error 4 in btrfs[400000+83000]
> 
> # btrfs rescue super-recover -v /dev/sda
> All Devices:
>         Device: id = 3, name = /dev/sdc
>         Device: id = 2, name = /dev/sdb
>         Device: id = 1, name = /dev/sda
> 
> Before Recovering:
>         [All good supers]:
>                 device name = /dev/sdc
>                 superblock bytenr = 65536
> 
>                 device name = /dev/sdc
>                 superblock bytenr = 67108864
> 
>                 device name = /dev/sdc
>                 superblock bytenr = 274877906944
> 
>                 device name = /dev/sdb
>                 superblock bytenr = 65536
> 
>                 device name = /dev/sdb
>                 superblock bytenr = 67108864
> 
>                 device name = /dev/sdb
>                 superblock bytenr = 274877906944
> 
>                 device name = /dev/sda
>                 superblock bytenr = 65536
> 
>                 device name = /dev/sda
>                 superblock bytenr = 67108864
> 
>                 device name = /dev/sda
>                 superblock bytenr = 274877906944
> 
>         [All bad supers]:
> 
> All supers are valid, no need to recover
> 
> # btrfs-show-super /dev/sda
> superblock: bytenr=65536, device=/dev/sda
> ---------------------------------------------------------
> csum                    0x61b509bb [match]
> bytenr                  65536
> flags                   0x1
> magic                   _BHRfS_M [match]
> fsid                    27ef2638-b50a-4243-80ed-40c3733ec11d
> label
> generation              69462
> root                    1648640000
> sys_array_size          290
> chunk_root_generation   48545
> root_level              1
> chunk_root              21020672
> chunk_root_level        1
> log_root                0
> log_root_transid        0
> log_root_level          0
> total_bytes             4000819544064
> bytes_used              2743528714240
> sectorsize              4096
> nodesize                16384
> leafsize                16384
> stripesize              4096
> root_dir                6
> num_devices             4
> compat_flags            0x0
> compat_ro_flags         0x0
> incompat_flags          0xe1
>                         ( MIXED_BACKREF |
>                           BIG_METADATA |
>                           EXTENDED_IREF |
>                           RAID56 )
> csum_type               0
> csum_size               4
> cache_generation        69462
> uuid_tree_generation    69462
> dev_item.uuid           70f4650c-e01d-4613-bd7a-a6834c1c44bb
> dev_item.fsid           27ef2638-b50a-4243-80ed-40c3733ec11d [match]
> dev_item.type           0
> dev_item.total_bytes    1000204886016
> dev_item.bytes_used     966057263104
> 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
> 
> thx for helps
> 

-- 
Hugo Mills             | You can't expect a boy to be vicious until he's gone
hugo@... carfax.org.uk | to a good school.
http://carfax.org.uk/  |
PGP: E2AB1DE4          |                                                  Saki

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