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* bcache cant register cache device "bad csum" & "bad magic"
@ 2015-08-15 17:54 Георгий Стариков
       [not found] ` <77CE39AF-AD1A-4F4D-94EB-7D199EC60C74@profihost.ag>
  0 siblings, 1 reply; 3+ messages in thread
From: Георгий Стариков @ 2015-08-15 17:54 UTC (permalink / raw)
  To: linux-bcache

Hi!
I lost bcache device after a reboot and dmesg contains the following:
[   26.991085] bcache: prio_read() bad csum reading priorities
[   26.991088] bcache: prio_read() bad magic reading priorities
[   26.991425] attempt to access beyond end of device
[   26.991428] sdc: rw=48, want=3405010361836132352, limit=468862128
[   26.991430] bcache: error on 4ca0fbc9-d20b-4a3d-bbd1-38d9a5810c27:
accessing                                            priorities,
disabling caching

how to fix it?

i am using the following fix (recreate cache device with the old cuid)
and it works till next reboot.

# bcache-super-show /dev/sdc
sb.magic                ok
sb.first_sector         8 [match]
sb.csum                 F19B35ED4C357841 [match]
sb.version              3 [cache device]

dev.label               (empty)
dev.uuid                7dddbf16-ca58-48e3-82d8-da47ae7726dc
dev.sectors_per_block   1
dev.sectors_per_bucket  1024
dev.cache.first_sector  1024
dev.cache.cache_sectors 468860928
dev.cache.total_sectors 468861952
dev.cache.ordered       yes
dev.cache.discard       no
dev.cache.pos           0
dev.cache.replacement   0 [lru]

cset.uuid               4ca0fbc9-d20b-4a3d-bbd1-38d9a5810c27

# make-bcache -C --cset-uuid 4ca0fbc9-d20b-4a3d-bbd1-38d9a5810c27 /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache

 make-bcache -C --wipe-bcache --cset-uuid
4ca0fbc9-d20b-4a3d-bbd1-38d9a5810c27 /dev/sdc
Device /dev/sdc already has a non-bcache superblock, remove it using
wipefs and wipefs -a

# wipefs -a /dev/sdc

# make-bcache -C --wipe-bcache --cset-uuid
4ca0fbc9-d20b-4a3d-bbd1-38d9a5810c27 /dev/sdc
UUID:                   f7d97543-69ea-4636-a4ff-ab925ab5abdd
Set UUID:               4ca0fbc9-d20b-4a3d-bbd1-38d9a5810c27
version:                0
nbuckets:               457873
block_size:             1
bucket_size:            1024
nr_in_set:              1
nr_this_dev:            0
first_bucket:           1

# echo /dev/sdc > /sys/fs/bcache/register

dmesg:
[42999.742342] bcache: run_cache_set() invalidating existing data
[42999.900046] bcache: bch_cached_dev_attach() Caching md0 as bcache0
on set 4ca0fbc9-d20b-4a3d-bbd1-38d9a5810c27
[42999.900067] bcache: register_cache() registered cache device sdc
[43002.019693] EXT4-fs (bcache0): recovery complete
[43002.043362] EXT4-fs (bcache0): mounted filesystem with ordered data
mode. Opts: discard,errors=remount-ro

and final steps:
# echo writethrough > /sys/block/bcache0/bcache/cache_mode
# echo 128k > /sys/block/bcache0/bcache/sequential_cutoff

# ./bcache-status -s
--- bcache ---
Device                      /dev/bcache0 (251:0)
UUID                        4ca0fbc9-d20b-4a3d-bbd1-38d9a5810c27
Block Size                  0.50KiB
Bucket Size                 512.00KiB
Congested?                  False
Read Congestion             2.0ms
Write Congestion            20.0ms
Total Cache Size            223.57GiB
Total Cache Used            2.24GiB     (0%)
Total Cache Unused          221.34GiB   (99%)
Dirty Data                  0B  (0%)
Evictable Cache             223.57GiB   (100%)
Replacement Policy          [lru] fifo random
Cache Mode                  [writethrough] writeback writearound none
Total Hits                  139 (3%)
Total Misses                3816
Total Bypass Hits           0
Total Bypass Misses         0
Total Bypassed              0B
--- Backing Device ---
  Device                    /dev/md0 (9:0)
  Size                      5.46TiB
  Cache Mode                [writethrough] writeback writearound none
  Readahead                 0
  Sequential Cutoff         128.00KiB
  Merge sequential?         False
  State                     clean
  Writeback?                True
  Dirty Data                0B
  Total Hits                139 (3%)
  Total Misses              3816
  Total Bypass Hits         0
  Total Bypass Misses       0
  Total Bypassed            0B
--- Cache Device ---
  Device                    /dev/sdc (8:32)
  Size                      223.57GiB
  Block Size                0.50KiB
  Bucket Size               512.00KiB
  Replacement Policy        [lru] fifo random
  Discard?                  False
  I/O Errors                0
  Metadata Written          1.60MiB
  Data Written              19.20MiB
  Buckets                   457873
  Cache Used                2.24GiB     (0%)
  Cache Unused              221.34GiB   (99%)

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2015-08-15 18:25 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2015-08-15 17:54 bcache cant register cache device "bad csum" & "bad magic" Георгий Стариков
     [not found] ` <77CE39AF-AD1A-4F4D-94EB-7D199EC60C74@profihost.ag>
2015-08-15 18:24   ` Георгий Стариков
2015-08-15 18:25     ` Stefan Priebe

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