Thank you Ilya for confirmation!
Tony
________________________________________
From: Ilya Dryomov <idryomov@xxxxxxxxx>
Sent: August 4, 2023 04:51 AM
To: Tony Liu
Cc: dev@xxxxxxx; ceph-users@xxxxxxx
Subject: Re: [ceph-users] snapshot timestamp
On Fri, Aug 4, 2023 at 7:49 AM Tony Liu <tonyliu0592@xxxxxxxxxxx> wrote:
>
> Hi,
>
> We know snapshot is on a point of time. Is this point of time tracked internally by
> some sort of sequence number, or the timestamp showed by "snap ls", or something else?
Hi Tony,
The timestamp in "rbd snap ls" output is the snapshot creation
timestamp.
>
> I noticed that when "deep cp", the timestamps of all snapshot are changed to copy-time.
Correct -- exactly the same as the image creation timestamp (visible in
"rbd info" output).
> Say I create a snapshot at 1PM and make a copy at 3PM, the timestamp of snapshot in
> the copy is 3PM. If I rollback the copy to this snapshot, I'd assume it will actually bring me
> back to the state of 1PM. Is that correct?
Correct.
>
> If the above is true, I won't be able to rely on timestamp to track snapshots.
>
> Say I create a snapshot every hour and make a backup by copy at the end of the day.
> Then the original image is damaged and backup is used to restore the work. On this
> backup image, how do I know which snapshot was on 1PM, which was on 2PM, etc.?
> Any advices to track snapshots properly in such case?
I would suggest embedding that info along with any additional metadata
needed in the snapshot name.
Thanks,
Ilya
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