On Thu, Sep 15, 2016 at 12:54 PM, Nikolay Borisov <kernel@xxxxxxxx> wrote:
>
>
> On 09/15/2016 01:24 PM, Ilya Dryomov wrote:
>> 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.
>
> The machine has been up more than 2 and the dmesg has been rewritten
> several times for that time. Also the node is rather busy so there's
> plenty of irrelevant stuff in the dmesg. Grepped for rbd1/0 and found no
> strings containing them so it's unlikely you will get anything useful.
Kernel messages are logged, you can get to them with journalctl -k or
syslog. Grep for libceph?
>
>>
>> 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/')
>
> watcher=xx.xxx.xxx.xx:0/3416829538 client.157729 cookie=673
> watcher=xx.xxx.xxx.xx:0/3416829538 client.157729 cookie=676
What's the output of
$ cat /sys/bus/rbd/devices/47/client_id
$ cat /sys/bus/rbd/devices/1/client_id
>
>
>>
>> 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?
>
> That would take a bit more time since it involves downtime to production
> workloads.
>
> Btw, are you on IRC in ceph/ceph-devel ?
dis on #ceph-devel, but I'd rather do this via email.
Thanks,
Ilya
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