[PVE-User] excessive I/O latency during CEPH rebuild
elacunza at binovo.es
Tue Oct 28 16:11:08 CET 2014
You only have 3 osd in ceph cluster?
What about journals? Are they inline or in a separate (ssd?) disk?
What about network? Do you have an phisically independent network for
proxmox/vms and ceph?
We have a currently 6-osd 3-node ceph cluster; doing an out/in of a
osd, doesn't create a very high impact. If you in a new osd (replace a
disk) the impact is noticeable but our ~30 vms were yet workable. We do
have different physicall networks for proxmox/VMs and ceph. (1gbit)
On 28/10/14 16:03, Adam Thompson wrote:
> I'm seeing ridiculous I/O latency after out'ing and re-in'ing a disk
> in the CEPH array; the OSD monitor tab shows two OSDs (i.e. disks)
> having latency above 10msec - they're both in the 200ms range - but
> reading a single uncached sector from a virtual disk takes >10sec.
> It's bad enough that all my virtualized DNS servers are timing out and
> this, of course, directly impacts service.
> During normal (non-rebuild, non-rebalance) operations, CEPH is not
> terribly fast to write, but delivers acceptable read speeds.
> Where do I start looking for problems? Are there any knobs I should
> be tweaking for CEPH?
Zuzendari Teknikoa / Director Técnico
Binovo IT Human Project, S.L.
Astigarraga bidea 2, planta 6 dcha., ofi. 3-2; 20180 Oiartzun (Gipuzkoa)
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