[PVE-User] Proxmox with ceph storage VM performance strangeness

Alwin Antreich a.antreich at proxmox.com
Tue Apr 21 16:01:51 CEST 2020

On Tue, Apr 21, 2020 at 03:34:47PM +0200, Rainer Krienke wrote:
> Hello,
> just wanted to thank you for your help and to tell you that I found the
> culprit that made my read-perfomance look rarther small on a proxmox VM
> with a LV based on 4 disks (rdbs). The best result using bonnie++ as a
> test was about 100MBytes/sec on a single VM read performance.
> I remembered that right after I switched to LVM striping I had tested
> the default block size LVM would use which was 64K. I found this value
> rather small and replaces it by 512K, which increased read and write
> speed.
> I remenbered this fact and again changed the stripe size to the default
> RBD object size which is 4MB. Using this value the read performance went
> up to 400MBytes/sec and if I run two bonnies on two different VMs the
> total read performance in ceph is about 800MBytes/sec
> The write performance in this 2VMs test is about 1.2GByte/sec.
The 4 MB chunk size is good for Ceph. But how is the intended workload
performing on those VMs?


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