On 29 August 2015 at 00:53, Tony Nelson <tnelson@xxxxxxxxxxxxx> wrote:
I recently built a 3 node Proxmox cluster for my office. I’d like to get HA setup, and the Proxmox book recommends Ceph. I’ve been reading the documentation and watching videos, and I think I have a grasp on the basics, but I don’t need anywhere near a petabyte of storage.
I’m considering servers w/ 12 drive bays, 2 SDD mirrored for the OS, 2 SDDs for journals and the other 8 for OSDs. I was going to purchase 3 identical servers, and use my 3 Proxmox servers as the monitors, with of course GB networking in between. Obviously this is very vague, but I’m just getting started on the research.
I run a small 3 node Proxmox cluster for our office as well with Ceph, but I'd now recommend against using Ceph for small setups like ours.
- Maintenance headache. Ceph requires a lot of tweaking to get started and a lot of ongoing monitoring, plus a fair bit of skill. If you're running the show yourself (as typical in small businesses) its quite stressful. Who's going to fix the ceph cluster when a osd goes down when you're on holiday?
- Performance. Its terrible on small clusters. I've setup a iSCSI over ZFS for a server and its orders of magnitude better at I/O. And I haven't even configured multipath yet.
- Flexibility. Much much easier to expand or replace disks on my ZFS server.
The redundancy is good, I can reboot a ceph node for maintenance and it recovers very quickly (much quicker than glusterfs), but cluster performance suffers badly when a node is down so in practice its of limited utility.
I'm coming to the realisation that for us performance and ease of administration is more valuable than 100% uptime. Worst case (Storage server dies) we could rebuild from backups in a day. Essentials could be restored in a hour. I could experiment with ongoing ZFS replications to a backup server that makes that even quicker.
Thats for use - your requirements may be different. And of course once you get into truly large deployments, ceph comes into its own.
--
Lindsay
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