[linux-lvm] Snapshot behavior on classic LVM vs ThinLVM

[Zdenek Kabelac]

Dne 16.5.2017 v 09:53 Gionatan Danti napsal(a):
> On 15/05/2017 17:33, Zdenek Kabelac wrote:> Ever tested this:
>>
>> mount -o errors=remount-ro,data=journal ?
> 
> Yes, I tested it - same behavior: a full thinpool does *not* immediately put 
> the filesystem in a read-only state, even when using sync/fsync and 
> "errorwhenfull=y".

Hi

Somehow I think you've rather made a mistake during your test (or you have 
buggy kernel). Can you take full log of your test  show all options are
properly applied

i.e. dmesg log +  /proc/self/mountinfo report showing all options used for 
mountpoint and kernel version in use.

IMHO you should get something like this in dmesg once your pool gets out of 
space and starts to return error on write:

----
Aborting journal on device dm-4-8.
EXT4-fs error (device dm-4): ext4_journal_check_start:60: Detected aborted journal
EXT4-fs (dm-4): Remounting filesystem read-only
----


Clearly when you specify 'data=journal'  even write failure of data will cause 
journal error and thus remount-ro reaction (it least on my box does it) - but 
such usage is noticeable slower compared with 'ordered' mode.


Regards

Zdenek