On Thu, Nov 21, 2013 at 10:13 AM, John-Paul Robinson <jpr@xxxxxxx> wrote: > Is this statement accurate? > > As I understand DRBD, you can replicate online block devices reliably, > but with Ceph the replication for RBD images requires that the file > system be offline. It's not clear to me what replication you're asking about with Ceph here. Ceph is internally replicating the block device to keep it available in case of server failures, and that's all happening online. If you want a logically distinct copy (? this seems to be what Dimitri is referring to with adding a 3rd DRBD copy on another node) then that model is a lot different than in the classical storage world — it might be that you're saying "I want 3-copy durability instead of 2-copy" which you can do online (for all images stored in a given pool); or you might be after a copy you can use as a stable backup point, which you can do by taking a snapshot of the image (but here you probably want to quiesce the filesystem, yes); or you might be after something completely different which I'm not thinking of... -Greg Software Engineer #42 @ http://inktank.com | http://ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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