On 2014-12-06 05:57, Chris Murphy wrote:
Right - so we're getting these:
# parted /dev/sdb u s p
Model: ATA ST3000DM001-9YN1 (scsi)
Disk /dev/sdb: 5860533168s
Sector size (logical/physical): 512B/4096B
OK it's a 4096 byte physical sector drive so you have to use the
bs=4096 command with the proper seek value (which is based on the bs
value).
Yep.
So here is what I did:
# echo 2262535088 / 8|bc # (512 * 8 = 4096)
282816886
* verify if it's this place
# dd if=/dev/sdb of=/dev/null bs=4096 count=1 skip=282816886
dd: reading `/dev/sdb': Input/output error
0+0 records in
0+0 records out
0 bytes (0 B) copied, 2.83002 s, 0.0 kB/s
* overwrite it:
dd if=/dev/zero of=/dev/sdb bs=4096 count=1 seek=282816886
1+0 records in
1+0 records out
4096 bytes (4.1 kB) copied, 3.0277e-05 s, 135 MB/s
* try to read it:
# dd if=/dev/sdb of=/dev/null bs=4096 count=1 skip=282816886
1+0 records in
1+0 records out
4096 bytes (4.1 kB) copied, 2.6204e-05 s, 156 MB/s
* try to read with the old skip value (repeat for 2262535088 -
2262535095, or use a different count value - this is where we were
getting the errors, it's also 8 * 512):
dd if=/dev/sdb of=/dev/null count=1 skip=2262535088
...
dd if=/dev/sdb of=/dev/null count=1 skip=2262535095
* Unfortunately this is still an error for btrfs, because the checksum
does not match:
# time btrfs device delete missing /home
ERROR: error removing the device 'missing' - Input/output error
# dmesg -c
[84200.109774] BTRFS info (device sda4): relocating block group
1375492636672 flags 17
[84203.635559] BTRFS info (device sda4): csum failed ino 261 off
384262144 csum 2566472073 expected csum 4193010590
[84203.650980] BTRFS info (device sda4): csum failed ino 261 off
384262144 csum 2566472073 expected csum 4193010590
[84203.651444] BTRFS info (device sda4): csum failed ino 261 off
384262144 csum 2566472073 expected csum 4193010590
* remounting with nodatacow (nodatasum) does not help (since it's for
new data)
* let's find the inode printing the error - turned out to be a directory
- so created a new one, moved the data from the "corrupt one", removed
the directory with that inode:
# find /home -mount -inum 261
/home/backup/ma-int/weekly
* repeat for any other found:
# dmesg -c
[85197.300494] BTRFS info (device sda4): relocating block group
1375492636672 flags 17
[85200.448713] BTRFS info (device sda4): csum failed ino 267 off
384262144 csum 2566472073 expected csum 4193010590
[85200.472581] BTRFS info (device sda4): csum failed ino 267 off
384262144 csum 2566472073 expected csum 4193010590
[85200.473551] BTRFS info (device sda4): csum failed ino 267 off
384262144 csum 2566472073 expected csum 4193010590
* unfortunately it never ends - let's say we have
/home/backup/ma-int/weekly, which we "fixed" with:
mkdir /home/backup/ma-int/weekly.tmp
mv /home/backup/ma-int/weekly/* /home/backup/ma-int/weekly.tmp
rmdir /home/backup/ma-int/weekly
After we run again btrfs device delete missing /home, the newly created
directory eventually (/home/backup/ma-int/weekly.tmp) is being detected
as "csum failed ino ...".
--
Tomasz Chmielewski
http://www.sslrack.com
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