> Hi,
> 
> just one question coming to mind, if you intend to migrate the images 
> separately, is it really necessary to set up mirroring? You could just 'rbd 
> export' on the source cluster and 'rbd import' on the destination cluster.

That can be slower if using a pipe, and require staging space one doesn’t have 
if using and transferring files.

And of course it’s right out if the RBD volume is currently attached.




> 
> 
> Zitat von Anthony D'Atri <[email protected]>:
> 
>>> 
>>> I would like to use mirroring to facilitate migrating from an existing
>>> Nautilus cluster to a new cluster running Reef.  RIght now I'm looking at
>>> RBD mirroring.  I have studied the RBD Mirroring section of the
>>> documentation, but it is unclear to me which commands need to be issued on
>>> each cluster and, for commands that have both clusters as arguments, when
>>> to specify site-a where vs. site-b.
>> 
>> I won’t go into the nitty-gritty, but note that you’ll likely run the 
>> rbd-mirror daemon on the destination cluster, and it will need reachability 
>> to all of the source cluster’s mons and OSDs.  Maybe mgrs, not sure.
>> 
>>> Another concern:  Both the old and new cluster internally have the default
>>> name 'Ceph' - when I set up the second cluster I saw no obvious reason to
>>> change from the default.  If these will cause a problem with mirroring, is
>>> there a workaround?
>> 
>> The docs used to imply that the clusters need to have distinct vanity names, 
>> but that was never actually the case — and vanity names are no longer 
>> supported for clusters.
>> 
>> The ceph.conf files for both clusters need to be distinct and present on the 
>> system where rbd-mirror runs.  You can do this by putting them in different 
>> subdirectories or calling them like cephsource.conf and cephdest.conf.  The 
>> filenames are arbitrary, you’ll just have to specify them when setting up 
>> rbd-mirror peers.
>> 
>> 
>>> In the long run I will also be migrating a bunch of RGW data.  If there are
>>> advantages to using mirroring for this I'd be glad to know.
>> 
>> Whole different ballgame.  You can use multisite or rclone or the new Clyso 
>> “Chorus” tool for that.
>> 
>>> (BTW, the plan is to gradually decommission the systems from the old
>>> cluster and add them to the new cluster.  In this context, I am looking to
>>> enable and disable mirroring on specific RBD images and RGW buckets as the
>>> client workload is migrated from accessing the old cluster to accessing the
>>> new.
>> 
>> I’ve migrated thousands of RBD volumes between clusters this way.  It gets a 
>> bit tricky if a volume is currently attached.
>> 
>>> 
>>> Thanks.
>>> 
>>> -Dave
>>> 
>>> --
>>> Dave Hall
>>> Binghamton University
>>> [email protected]
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