CEPH multiple MDS on the same node

encore

Member
May 4, 2018
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Hi,

I am running a 5-node ceph cluster (Octopus) and when I increased the number of active MDs from 2 to 4 I experienced a gain of performance in my CephFS.
Since I have a lot of client using the cephfs pool I think it might be a good idea to increase the number of MDs even more.

https://docs.ceph.com/en/octopus/cephfs/multimds/
Ceph supports multiple MDs per node since octopus but unfortunately proxmox GUI does not.

Would it work to create multiple MDs as described above trough the CLI even if the PVE GUI does not support it?

Thank you!
 
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dlasher

Active Member
Mar 23, 2011
137
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Fair question, I'd like to see an answer as well - given pretty solid test data showing significant advantages to multiple MDS's (like this : https://croit.io/blog/ceph-performance-test-and-optimization) I'd love to see support for more than one MDS per server.

... the CPU usage by each active ceph-mds process comes close to 100%. In other words, with only four active MDSs, that’s about as fast as the cluster can go in these metadata-intensive benchmarks.....In fact, we found that even two MDSs per host are not enough to avoid the bottleneck. So we deployed 20 MDSs total - four per host, and made 16 of them active....
 
Last edited:

fiona

Proxmox Staff Member
Staff member
Aug 1, 2019
2,455
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Hi,
yes, this should be possible in the CLI. Use pveceph mds create --name <name> with different names to create multiple MDS on the same node. Since it's possible to create multiple Ceph filesystems via Proxmox VE GUI since 7.1, this likely makes sense to expose in the GUI too. Feel free to create a feature request for it.
 

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