On Thu, Sep 15, 2016 at 10:22 AM, Nikolay Borisov
<n.borisov@xxxxxxxxxxxxxx> wrote:
>
>
> On 09/15/2016 09:22 AM, Nikolay Borisov wrote:
>>
>>
>> On 09/14/2016 05:53 PM, Ilya Dryomov wrote:
>>> On Wed, Sep 14, 2016 at 3:30 PM, Nikolay Borisov <kernel@xxxxxxxx> wrote:
>>>>
>>>>
>>>> On 09/14/2016 02:55 PM, Ilya Dryomov wrote:
>>>>> On Wed, Sep 14, 2016 at 9:01 AM, Nikolay Borisov <kernel@xxxxxxxx> wrote:
>>>>>>
>>>>>>
>>>>>> On 09/14/2016 09:55 AM, Adrian Saul wrote:
>>>>>>>
>>>>>>> I found I could ignore the XFS issues and just mount it with the appropriate options (below from my backup scripts):
>>>>>>>
>>>>>>> #
>>>>>>> # Mount with nouuid (conflicting XFS) and norecovery (ro snapshot)
>>>>>>> #
>>>>>>> if ! mount -o ro,nouuid,norecovery $SNAPDEV /backup${FS}; then
>>>>>>> echo "FAILED: Unable to mount snapshot $DATESTAMP of $FS - cleaning up"
>>>>>>> rbd unmap $SNAPDEV
>>>>>>> rbd snap rm ${RBDPATH}@${DATESTAMP}
>>>>>>> exit 3;
>>>>>>> fi
>>>>>>> echo "Backup snapshot of $RBDPATH mounted at: /backup${FS}"
>>>>>>>
>>>>>>> It's impossible without clones to do it without norecovery.
>>>>>>
>>>>>> But shouldn't freezing the fs and doing a snapshot constitute a "clean
>>>>>> unmount" hence no need to recover on the next mount (of the snapshot) -
>>>>>> Ilya?
>>>>>
>>>>> I *thought* it should (well, except for orphan inodes), but now I'm not
>>>>> sure. Have you tried reproducing with loop devices yet?
>>>>
>>>> Here is what the checksum tests showed:
>>>>
>>>> fsfreeze -f /mountpoit
>>>> md5sum /dev/rbd0
>>>> f33c926373ad604da674bcbfbe6460c5 /dev/rbd0
>>>> rbd snap create xx@xxx && rbd snap protect xx@xxx
>>>> rbd map xx@xxx
>>>> md5sum /dev/rbd1
>>>> 6f702740281874632c73aeb2c0fcf34a /dev/rbd1
>>>>
>>>> where rbd1 is a snapshot of the rbd0 device. So the checksum is indeed
>>>> different, worrying.
>>>
>>> Sorry, for the filesystem device you should do
>>>
>>> md5sum <(dd if=/dev/rbd0 iflag=direct bs=8M)
>>>
>>> to get what's actually on disk, so that it's apples to apples.
>>
>> root@alxc13:~# rbd showmapped |egrep "device|c11579"
>> id pool image snap device
>> 47 rbd c11579 - /dev/rbd47
>> root@alxc13:~# fsfreeze -f /var/lxc/c11579
>> root@alxc13:~# md5sum <(dd if=/dev/rbd47 iflag=direct bs=8M)
>> 12800+0 records in
>> 12800+0 records out
>> 107374182400 bytes (107 GB) copied, 617.815 s, 174 MB/s
>> 2ddc99ce1b3ef51da1945d9da25ac296 /dev/fd/63 <--- Check sum after freeze
>> root@alxc13:~# rbd snap create rbd/c11579@snap_test
>> root@alxc13:~# rbd map c11579@snap_test
>> /dev/rbd1
>> root@alxc13:~# md5sum <(dd if=/dev/rbd1 iflag=direct bs=8M)
>> 12800+0 records in
>> 12800+0 records out
>> 107374182400 bytes (107 GB) copied, 610.043 s, 176 MB/s
>> 2ddc99ce1b3ef51da1945d9da25ac296 /dev/fd/63 <--- Check sum of snapshot
>> root@alxc13:~# md5sum <(dd if=/dev/rbd47 iflag=direct bs=8M)
>> 12800+0 records in
>> 12800+0 records out
>> 107374182400 bytes (107 GB) copied, 592.164 s, 181 MB/s
>> 2ddc99ce1b3ef51da1945d9da25ac296 /dev/fd/63 <--- Check sum of original device, not changed - GOOD
>> root@alxc13:~# file -s /dev/rbd1
>> /dev/rbd1: Linux rev 1.0 ext4 filesystem data (extents) (large files) (huge files)
>> root@alxc13:~# fsfreeze -u /var/lxc/c11579
>> root@alxc13:~# md5sum <(dd if=/dev/rbd47 iflag=direct bs=8M)
>> 12800+0 records in
>> 12800+0 records out
>> 107374182400 bytes (107 GB) copied, 647.01 s, 166 MB/s
>> 92b7182591d7d7380435cfdea79a8897 /dev/fd/63 <--- After unfreeze checksum is different - OK
>> root@alxc13:~# md5sum <(dd if=/dev/rbd1 iflag=direct bs=8M)
>> 12800+0 records in
>> 12800+0 records out
>> 107374182400 bytes (107 GB) copied, 590.556 s, 182 MB/s
>> bc3b68f0276c608d9435223f89589962 /dev/fd/63 <--- Why the heck the checksum of the snapshot is different after unfreeze? BAD?
>> root@alxc13:~# file -s /dev/rbd1
>> /dev/rbd1: Linux rev 1.0 ext4 filesystem data (needs journal recovery) (extents) (large files) (huge files)
>> root@alxc13:~#
>>
>
> And something even more peculiar - taking an md5sum some hours after the
> above test produced this:
>
> root@alxc13:~# md5sum <(dd if=/dev/rbd1 iflag=direct bs=8M)
> 12800+0 records in
> 12800+0 records out
> 107374182400 bytes (107 GB) copied, 636.836 s, 169 MB/s
> e68e41616489d41544cd873c73defb08 /dev/fd/63
>
> Meaning the read-only snapshot somehow has "mutated". E.g. it wasn't
> recreated, just the same old snapshot. Is this normal?
Hrm, I wonder if it missed a snapshot context update. Please pastebin
entire dmesg for that boot.
Have those devices been remapped or alxc13 rebooted since then? If
not, what's the output of
$ rados -p rbd listwatchers $(rbd info c11579 | grep block_name_prefix
| awk '{ print $2 }' | sed 's/rbd_data/rbd_header/')
and can you check whether that snapshot is continuing to mutate as the
image is mutated - freeze /var/lxc/c11579 again and check rbd47 and
rbd1?
Thanks,
Ilya
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