Somnath Roy <Somnath.Roy <at> sandisk.com> writes: > > Tom, > Good that you brought this up ! > I was also seeing the small writes during reads but forgot to mention in my last report on EC. > Basically, Ceph code base seems to be issuing small writes during reads and it is basically going to both > data/jounal (considering filestore backend) ..But, since data partition is syncing on every 5 sec , it is > not obvious there. > > Loic, > Could you please explain a bit more on this ? What exactly we are writing during reads ? > > Thanks & Regards > Somnath > > -----Original Message----- > From: ceph-devel-owner <at> vger.kernel.org [mailto:ceph-devel-owner <at> vger.kernel.org] On Behalf Of > Deneau, Tom > Sent: Wednesday, May 13, 2015 4:40 PM > To: ceph-devel > Subject: journal writes when running rados bench seq on ec pool > > I am running a rados bench seq read benchmark on an erasure-coded pool (k=2, m=1), > and recording the disk activity. I notice that I always see a small number of writes > to the journal partitions during the seq read run. (I always drop the caches on the osd nodes before starting > the seq read run). > > I never see this journal write behavior with a replicated pool and I didn't think there would be any journal > writes with either kind of pool on a read benchmark. > > The write activity is low enough that it's probably not that important performance-wise but I as just > curious as to what would cause this. > Was anyone able to explain these journal/data writes that occur during EC pool reads? -- 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
