[pve-devel] ceph octopus rbd benchmark

[Alexandre DERUMIER]

Hi,

I have done some benchmark with librbd octopus,

results are really great with new the write-around cache policy. (Simply need to enable cache=writeback in qemu)


Here some iops result with 1vm - 1disk -  4k block   iodepth=64, librbd, no iothread.



                        nautilus-cache=none     nautilus-cache=writeback          octopus-cache=none     octopus-cache=writeback
          
randread 4k                  62.1k                     25.2k                            61.1k                     60.8k
randwrite 4k                 27.7k                     19.5k                            34.5k                     53.0k
seqwrite 4k                  7850                      37.5k                            24.9k                     82.6k



We don't have anymore read degradation with cache=writeback,  and write performance is around 2,5x faster !
I think that when octopus will be ready for proxmox6, we could advise user to change the disk cache to writeback.
(and maybe select it as default in gui when an rbd storage is used for a new vm isk)