Feature #41905
openAdd ability to change fsid of cluster
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Description
There is a case where you want to change the fsid of a cluster: When you have splitted a cluster into two different cluster with their own MONs.
This procedure isn't easy, but it's doable.
You then end up with two clusters with the same fsid.
The fsid is recorded in multiple places:
- osdmap
- monmap
- Data store of OSDs
- ceph.conf
It would be nice if we can modify the fsid of an existing cluster (without downtime?)
Updated by Greg Farnum over 4 years ago
- Project changed from Ceph to RADOS
This sounds to me like the kind of thing we don't want to support directly. What's the use case for splitting a cluster up like that rather than creating new ones? There's a lot of danger in letting users change or set what's supposed to be a globally-unique identifier; how does this use case eclipse that in importance?
Updated by Wido den Hollander over 4 years ago
Splitting the cluster meant no data copy from A to B. Minimal downtime for the RGW application and no downtime for the RBD based VMs.
Yes, a copy would have worked, but that would have meant a lot of downtime.
We tried this procedure in a LAB and as it worked we performed it on production as well.