Re: Documentation for BTRFS error (device dev): bdev /dev/xx errs: wr 22, rd 0, flush 0, corrupt 0, gen 0

[Marc MERLIN <marc@merlins.org>]

On Tue, Feb 23, 2016 at 01:59:11PM -0800, Marc MERLIN wrote:
> I have a freshly created md5 array, with drives that I specifically
> scanned one by one block by block, and for good measure, I also scanned
> the entire software raid with a check command which took 3 days to run.
> 
> Everything passed.
> 
> Then, I made a bcache of that device, an ssd that seems to work fine
> otherwise (brand new), and dmcrypted the result
> 
> md5 - bache - dmcrypt - btrfs
> ssd /
> 
> Now, I'm copying data over with btrfs send, and I'm seeing these slowly
> show up and the write counter go up one by one.
> BTRFS error (device dm-7): bdev /dev/mapper/oldds1 errs: wr 17, rd 0, flush 0, corrupt 0, gen 0
> 
> Where is the documentation for those counters?
> Is the write error fatal, or a recovered error?
> Should I consider that my filesystem is corrupted as soon as any of
> those counters go up?
> (I couldn't find an exact meaning of each of them)
> 

Sadly, this problem hasn't gone away
[ 2381.333412] BTRFS error (device dm-5): bdev /dev/mapper/oldds1 errs: wr 298, rd 0, flush 0, corrupt 0, gen 0

I'm really trying to make sense out of it.
Are those recovered errors (bad IO, command was retried, things worked
after that), fatal errors (data loss)

That md5 is in a disk shelf at the end of a longish esata cable. It's
possible that the cable is bad, or it couuld be something else entirely.
I'm still trying to understand the error so that I can diagnose and
address it properly.

Thanks,
Marc
-- 
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