Hi, Am 06.01.2015 um 04:44 schrieb Alexandre DERUMIER: > Hi Stefan, > > Do you see a difference if you force filestore journal writeahead for btrfs instead parrallel ? > > filestore journal writeahead = 1 > filestore journal parallel = 0 i already tested filestore btrfs snap = false which automatically disabled parallel write. Stefan > ----- Mail original ----- > De: "Stefan Priebe" <s.priebe@xxxxxxxxxxxx> > À: "Mark Nelson" <mnelson@xxxxxxxxxx>, "Sage Weil" <sage@xxxxxxxxxxxx> > Cc: "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx> > Envoyé: Lundi 5 Janvier 2015 21:33:22 > Objet: Re: 10 times higher disk load with btrfs > > Am 05.01.2015 um 21:29 schrieb Mark Nelson: >> >> >> On 01/05/2015 02:20 PM, Stefan Priebe wrote: >>> Hi Sage, >>> >>> Am 05.01.2015 um 20:25 schrieb Sage Weil: >>>> On Mon, 5 Jan 2015, Stefan Priebe wrote: >>>>> >>>>> Am 05.01.2015 um 19:36 schrieb Stefan Priebe: >>>>>> Hi devs, >>>>>> >>>>>> while btrfs is now declared as stable ;-) i wanted to retest btrfs on >>>>>> our production cluster on 2 out of 54 osds. So if they crash it >>>>>> doesn't >>>>>> hurt. >>>>>> >>>>>> While if those OSDs run XFS have spikes of 20MB/s every 4-7s. The same >>>>>> OSDs after formatting them with btrfs have spikes of 190MB/s every >>>>>> 4-7s. >>>>>> >>>>>> Why does just another filesystem raises the disk load by a factor of >>>>>> 10? >>>>> >>>>> OK this seems to happen cause ceph is creating every 5s a new >>>>> subvolume / >>>>> snap. Is this really expected / needed? >>>> >>>> You can disable it with >>>> >>>> filestore btrfs snap = false >>>> >>>> I'm curious how much this drops the load down; originally the >>>> snaps were no more expensive than a regular sync but perhaps this >>>> has changed... >>> >>> - with XFS the average write is at 9Mb/s >>> - with btrfs (filestore_btrfs_snap=true) write is at 40Mb/s >>> - with btrfs (filestore_btrfs_snap=false) write is at 20Mb/s >> >> Is that the average and not the spikes? It looks like before the spikes >> were 20MB/s and 190MB/s? > > Yes these are average values. > > Spikes: > - with XFS the spike write is at 20Mb/s > - with btrfs (filestore_btrfs_snap=true) spike write is 200Mb/s > - with btrfs (filestore_btrfs_snap=false) spike is still 185Mb/s but avg > is 1/2 (20Mb/s) see above > > >> >>> >>> Stefan >>> -- >>> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in >>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>> More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
