Ceph » rbd

1. A file is written to master, with a delay set on slave(10 mins).
2. Before the delay the master goes down abruptly (stopped the mirror service).
3. The data written on master is not yet synced to slave.

image-2:
global_id: 97551f32-2ac3-4df7-93a4-95a73d93b3e8
state: up+replaying
description: replaying, master_position=[object_number=7, tag_tid=2, entry_tid=25599], mirror_position=[], entries_behind_master=25602
last_update: 2017-09-23 16:15:02

4. Force promoted the slave to become primary.

5. After 10 minutes, data got synced on slave(entries_behind_master became 0)
During this time it was in up+replaying' state , after the delay state changed to 'up+stopped'(description: force promoted)

image-2:
global_id: 97551f32-2ac3-4df7-93a4-95a73d93b3e8
state: up+replaying
description: replaying, master_position=[object_number=7, tag_tid=2, entry_tid=25599], mirror_position=[object_number=7, tag_tid=2, entry_tid=25599], entries_behind_master=0
last_update: 2017-09-23 16:25:54

6. Brought back the master, demoted it and did a re-sync.

$rbd mirror image status data/image-2 --cluster master
image-2:
global_id: f84a899f-909e-4e23-9428-ee31c5ca14fa
state: up+replaying
description: replaying, master_position=[object_number=3, tag_tid=3, entry_tid=3], mirror_position=[object_number=3, tag_tid=3, entry_tid=3], entries_behind_master=0
last_update: 2017-09-23 16:27:58

7. Checked the size of the images on both clusters.(wired snap was created)

Master:
$sudo rbd du -p data --cluster master
warning: fast-diff map is not enabled for image-2. operation may be slow.
NAME PROVISIONED USED
image-2@.rbd-mirror.bc392583-5662-4721-8726-55573351bd8f.a96731e9-d9a0-4c7b-8b96-e844e8502421 1024M 152M
image-2
1024M 0
<TOTAL>
1024M 152M

slave:
$sudo rbd du -p data --cluster slave
warning: fast-diff map is not enabled for image-2. operation may be slow.
NAME PROVISIONED USED
image-2@.rbd-mirror.bc392583-5662-4721-8726-55573351bd8f.a96731e9-d9a0-4c7b-8b96-e844e8502421 1024M 0
image-2
1024M 0
<TOTAL>
1024M 0