[DRBD-user] drbd with a third node diskless - how ?
pbraun at nethence.com
Wed Jun 23 23:04:59 CEST 2021
> At the moment i do this as a proof if it is possible to build a proxmox
> cluster with 2 diskfull nodes, 1 quorum node (diskless)
> and replicated storage. My actual hobbycluster works since years in
> similar way. Proxmox have no solution for this usecase
> Ceph needs to much hardware and seems to be very complicate , ZFS is not
> usefull because its async.
I've seen Ceph RBD working well with Proxmox (and maybe 3 nodes are
- if we mess something up, it's becomes VERY bad. Ceph is dangerous.
it's a specialty on its own, not just for any storage engineer. and
even so, it would still be scary to me, thanks to its complexity and
bloated feature set (the originating CRUSH paper shows use-cases aiming
at GAFAM instead of explaining what matters, the algorithm itself).
- I suppose its performance is not as good as DRBD farms because of the
additional processing required by the algorithm and/or other overheads
related to Ceph's non-trival design. I've seen a paper from Linbit
before, about performance comparison between Ceph and DRBD, but I cannot
find it back.
I also still wonder about the space usage of Ceph block replicas. I am
not sure it truly offers the advantages of, say RAID-5 over RAID-1. But
this now really off-topic.
What ZFS feature, tool or wrapper are you referring to? I remember some
guy told me about a convergent FreeBSD ZFS & jail farm, many years ago,
and still wonder how on earth he did manage to do that, as ZFS is not
network-oriented (or was it at the time).
> DRBD would be the best solution, i think. The right tool for this job.
I agree, obviously. FreeBSD has HAST tho, but no diskless feature.
> Can you give me a hint how to configure that ? Do you use proxmox ? The
> proxmox plugin is only for linstor i think.
On community XEN, guests have a configuration with a line pointing at
the virtual disk e.g.
disk = ['phy:/dev/drbd1,xvda1,w']
so as long as you've allowed dual-primaries (even if that's actually
used very temporarily), you're good already, be it a diskfull or
diskless DRBD device.
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