BTRFS csum Warnings


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I just changed hardware this morning and I noticed that I am getting BTRFS csum warnings. It seems to coincide with me using my Windows 10 VM. This particular VM's vdisk is located on my cache drive. I've run a btrfs scrub and it reported no errors. What should I do next? Should the vdisk have checksum disabled?

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1 hour ago, johnnie.black said:

There's no problem having checksum enable for vdisks but it is strange scrub not reporting errors, please run a new scrub a post the output here as well as new diags grabbed after the scrub finishes.

  root@unRAID  ~  btrfs scrub start -B /dev/sdc1
scrub done for e10d5ffd-c05a-43db-b41e-e314f951b97a
	scrub started at Sat Oct 13 19:28:53 2018 and finished after 00:06:10
	total bytes scrubbed: 119.09GiB with 0 errors

 

 

unraid-diagnostics-20181013-1936.zip

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5 hours ago, johnnie.black said:

Try an offline check, with the array stopped:

 


btrfs check --readonly --check-data-csum /dev/sdc1

 

If still no errors I would backup/format/restore the cache.

 

Yeah, still no errors:

  root@unRAID  ~  btrfs check --readonly --check-data-csum /dev/sdc1
Checking filesystem on /dev/sdc1
UUID: e10d5ffd-c05a-43db-b41e-e314f951b97a
checking extents
checking free space cache
checking fs roots
checking csums against data
checking root refs
found 117959417856 bytes used, no error found
total csum bytes: 97811724
total tree bytes: 549404672
total fs tree bytes: 348897280
total extent tree bytes: 63881216
btree space waste bytes: 132519728
file data blocks allocated: 1556583190528
 referenced 94754942976

 

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The warnings seem to always come from the same inode:

 

Oct 14 09:16:59 unRAID kernel: BTRFS warning (device sdc1): csum failed root 5 ino 382101 off 2453172224 csum 0x2fbab702 expected csum 0x7ea1a571 mirror 1
Oct 14 09:16:59 unRAID kernel: BTRFS warning (device sdc1): csum failed root 5 ino 382101 off 2453536768 csum 0xba96ca2e expected csum 0x9be02cc0 mirror 1
Oct 14 09:17:01 unRAID kernel: BTRFS warning (device sdc1): csum failed root 5 ino 382101 off 2453172224 csum 0x9be02cc0 expected csum 0x7ea1a571 mirror 1
Oct 14 09:17:01 unRAID kernel: BTRFS warning (device sdc1): csum failed root 5 ino 382101 off 2453536768 csum 0x42186b7f expected csum 0x9be02cc0 mirror 1

That would probably be the vdisk file then. I'll try moving the vdisk from the cache and back on.

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41 minutes ago, johnnie.black said:

Try it, but it doesn't make much sense the scrub not detecting the error.

It was worth a try but it didn't do anything. I had made a change a couple weeks ago moving all my Docker containers to point directly to /mnt/cache rather than /mnt/user. I also changed the path to my VM's vdisk. I changed my vdisk location back to pointing at /mnt/user and the checksum warnings seem to have gone away.

 

Why would there be a difference between the two?

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