Re: Input/Output errors

["Szalma László" <dblaci@dblaci.hu>]

2016-02-24 05:37 keltezéssel, Chris Murphy írta:
> On Tue, Feb 23, 2016 at 8:02 PM, Kenny MacDermid
> <kenny.macdermid@gmail.com> wrote:
>
>> rw,noatime,compress=lzo,ssd,discard,space_cache,autodefrag,inode_cache
> It sounds like an ssd trim bug. I'd check the firmware for updates. If
> it's up to date, I'd drop discard mount option first and try to
> reproduce. Or just use the default mount options and try to reproduce,
> then add them back one at a time until you discover the culprit.
>
> Also, how many files/directories are there? inode_cache isn't
> recommended for most use cases. And space_cache is the default so it
> doesn't need to be listed.
>
>
>

As i wrote to the list a few weeks ago, this problem seems to be the 
same I have.

The difference:

- i use mount options: noatime,compress,nossd
- I don't use dm-crypt, but these machines are Xen pvms (there is a 
virtualization layer between btrfs and lvm)

The same:

- io error without any error or message in the dmesg.
- umount / mount always fixes the problem (for some time)

More info:

- these files are usually smalls (mysql myisam files, 10-20-50 kbyte 
size, without heave fragmentation)
- defrag don't help
- scrub always works (no errors) but not fix the errors
- no hw or hw read error on the block device (in any layer)
- get this problem with 4.4.1 kernel too (seems to be somewhat less 
frequent than before, but the problem happened with 3.18 and on)
- echo 3 > /proc/sys/vm/drop_caches    sometimes fixes the problem, but 
not every time
- the problem is happening rarely, sometimes there are days without error
- the problem is not for specific hardware or virtual machine

I can try any debug option or patch if needed.

László Szalma