Hi Simon,

What about the idea of creating the cluster over two data centers? Would it be possible to modify the crush map, so one pool gets replicated over those two data centers and if one fails, the other one would still be functional?

A stretched cluster is a valid approach, but you have to consider several things like MON quorum (you'll need a third MON independent of the two DCs) and failure domains and resiliency. The crush map and rules can be easily adjusted to reflect two DCs.

Additionally, would it be possible to prioritize one data center over the other? This would allow saving data from site1 to a pool on site2 in case of a disaster on site1, site2 would still have those Backups.

I don't think you can prioritize, maybe the primary-affinity of the OSDs in the second DC can be reduced to control that a little. But in a stretched cluster you don't have two pools that are replicated, the pools are stretched over those two DCs. Depending on the actual requirements you could for example have your (replicated) cephfs_data pool with size 4 and use a ruleset that stores 2 replicas in each DC. This also works with EC, of course. As long as your MONs have quorum one DC can fail and the data would still be available from the other DC. Regards, Eugen Zitat von Simon Sutter <ssutter@hosttech.ch>:

Thanks Stefan,

First of all, for a bit more context, we use this ceph cluster just for hot backups, so 99% write 1% read, no need for low latency.

Ok so the snapshot function would mean, we would have like a colder backup. Just like a snapshot of a VM, without any incremental functionality, which also means scheduled but huge transfer rates.

What about the idea of creating the cluster over two data centers? Would it be possible to modify the crush map, so one pool gets replicated over those two data centers and if one fails, the other one would still be functional? Additionally, would it be possible to prioritize one data center over the other? This would allow saving data from site1 to a pool on site2 in case of a disaster on site1, site2 would still have those Backups.

We have a 10G connection with around 0.5ms latency.

Thanks in advance, Simon

________________________________ Von: Stefan Kooman <stefan@bit.nl> Gesendet: Dienstag, 8. September 2020 11:38:29 An: Simon Sutter; ceph-users@ceph.io Betreff: Re: [ceph-users] Syncing cephfs from Ceph to Ceph

On 2020-09-08 11:22, Simon Sutter wrote:

...

Hello,

Is it possible to somehow sync a ceph from one site to a ceph form another site? I'm just using the cephfs feature and no block devices.

Being able to sync cephfs pools between two sites would be great for a hot backup, in case one site fails.

It's a work in progress [1]. This might do what you want to right now: [2]. Note: I haven't used [2] myself.

Gr. Stefan

[1]: https://docs.ceph.com/docs/master/dev/cephfs-mirroring/ [2]: https://github.com/oliveiradan/cephfs-sync _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io