Well, I'm sure that there was something which triggers the synchronization but that's definitely not the CLI command 'echo 3 > /proc/sys/vm/drop_caches'. So how can I trigger the delta transfer manually? Zhenshi Zhou <deaderzzs@gmail.com> 于2020年6月9日周二 下午8:02写道：
It claimed error when I promoted the non-primary image at first. But the command executed successfully after a while, without '--force'.
error: "rbd: error promoting image to primary2020-06-09 19:56:30.662 7f27e17fa700 -1 librbd::mirror::PromoteRequest: 0x558fa971fd20 handle_get_info: image is still primary within a remote cluster 2020-06-09 19:56:30.662 7f2804362b00 -1 librbd::api::Mirror: image_promote: failed to promote image"
Besides that, I wrote data by adding `date` to the end of a file, and flushed data by 'echo 3 > /proc/sys/vm/drop_caches'.
Jason Dillaman <jdillama@redhat.com> 于2020年6月9日周二 下午7:48写道：
On Tue, Jun 9, 2020 at 7:26 AM Zhenshi Zhou <deaderzzs@gmail.com> wrote:
I did promote the non-primary image, or I couldn't disable the image
mirror.
OK, that means that 100% of the data was properly transferred since it needs to replay previous events before it can get to the demotion event, replay that, so that you could non-force promote. How are you writing to the original primary image? Are you flushing your data?
Jason Dillaman <jdillama@redhat.com> 于2020年6月9日周二 下午7:19写道：
On Mon, Jun 8, 2020 at 11:42 PM Zhenshi Zhou <deaderzzs@gmail.com>
I have just done a test on rbd-mirror. Follow the steps: 1. deploy two new clusters, clusterA and clusterB 2. configure one-way replication from clusterA to clusterB with
rbd-mirror
3. write data to rbd_blk on clusterA once every 5 seconds 4. get information with 'rbd mirror image status rbd_blk', the "state" is "up+replaying" 5. demote image on clusterA(just wanna stop syncing and switch client connection to clusterB)
The result is: 1. I find that the "last_update" from "rbd mirror image status" updates every 30 seconds, which means I will lose at most 30s of data
The status updates are throttled but not the data transfer.
2. I stopped syncing on 11:02, while the data from rbd_blk on the clusterB is not newer than 10:50.
After demotion, you need to promote on the original non-primary side (w/o the --force) option. It won't let you non-force promote unless it has all the data copied. It will continue to copy data while the other side has been demoted until it fully catches up.
Did I have the wrong steps in the switching progress?
Zhenshi Zhou <deaderzzs@gmail.com> 于2020年6月9日周二 上午8:57写道：
Well, I'm afraid that the image didn't replay continuously, which
means I have some data lost.
The "rbd mirror image status" shows the image is replayed and its time is just before I demote the primary image. I lost about 24 hours' data and I'm not sure whether there is an interval between the synchronization.
I use version 14.2.9 and I deployed a one direction mirror.
Zhenshi Zhou <deaderzzs@gmail.com> 于2020年6月5日周五 上午10:22写道： > > Thank you for the clarification. That's very clear. > > Jason Dillaman <jdillama@redhat.com> 于2020年6月5日周五 上午12:46写道： >> >> On Thu, Jun 4, 2020 at 3:43 AM Zhenshi Zhou <deaderzzs@gmail.com> wrote: >> > >> > My condition is that the primary image being used while rbd-mirror sync. >> > I want to get the period between the two times of rbd-mirror
>> > increased data. >> > I will search those options you provided, thanks a lot :) >> >> When using the original (pre-Octopus) journal-based mirroring, once >> the initial sync completes to transfer the bulk of the image data from >> a point-in-time dynamic snapshot, any changes post sync will be >> replayed continuously from the stream of events written to the journal >> on the primary image. The "rbd mirror image status" against the >> non-primary image will provide more details about the current state of >> the journal replay. >> >> With the Octopus release, we now also support snapshot-based mirroring >> where we transfer any image deltas between two mirroring snapshots. >> These mirroring snapshots are different from user-created snapshots >> and their life-time is managed by RBD mirroring (i.e. they are >> automatically pruned when no longer needed). This version of mirroring >> probably more closely relates to your line of questioning since
>> period of replication is at whatever period you create new mirroring >> snapshots (provided your two clusters can keep up). >> >> > >> > Eugen Block <eblock@nde.ag> 于2020年6月4日周四 下午3:28写道： >> > >> > > The initial sync is a full image sync, the rest is based on
>> > > sets created. There are several options to control the mirroring, for >> > > example: >> > > >> > > rbd_journal_max_concurrent_object_sets >> > > rbd_mirror_concurrent_image_syncs >> > > rbd_mirror_leader_max_missed_heartbeats >> > > >> > > and many more. I'm not sure I fully understand what you're asking, >> > > maybe you could rephrase your question? >> > > >> > > >> > > Zitat von Zhenshi Zhou <deaderzzs@gmail.com>: >> > > >> > > > Hi Eugen, >> > > > >> > > > Thanks for the reply. If rbd-mirror constantly synchronize changes, >> > > > what frequency to replay once? I don't find any options I can config. >> > > > >> > > > Eugen Block <eblock@nde.ag> 于2020年6月4日周四 下午2:54写道： >> > > > >> > > >> Hi, >> > > >> >> > > >> that's the point of rbd-mirror, to constantly replay changes from the >> > > >> primary image to the remote image (if the rbd journal feature is >> > > >> enabled). >> > > >> >> > > >> >> > > >> Zitat von Zhenshi Zhou <deaderzzs@gmail.com>: >> > > >> >> > > >> > Hi all, >> > > >> > >> > > >> > I'm gonna deploy a rbd-mirror in order to sync image from clusterA to >> > > >> > clusterB. >> > > >> > The image will be used while syncing. I'm not sure if
wrote: transfer the the the object the rbd-mirror
>> > > will >> > > >> > sync image >> > > >> > continuously or not. If not, I will inform clients not to write data >> > > in >> > > >> it. >> > > >> > >> > > >> > Thanks. Regards >> > > >> > _______________________________________________ >> > > >> > ceph-users mailing list -- ceph-users@ceph.io >> > > >> > To unsubscribe send an email to ceph-users-leave@ceph.io >> > > >> >> > > >> >> > > >> _______________________________________________ >> > > >> ceph-users mailing list -- ceph-users@ceph.io >> > > >> To unsubscribe send an email to ceph-users-leave@ceph.io >> > > >> >> > > >> > > >> > > >> > > >> > _______________________________________________ >> > ceph-users mailing list -- ceph-users@ceph.io >> > To unsubscribe send an email to ceph-users-leave@ceph.io >> >> >> >> -- >> Jason >>
-- Jason
-- Jason