Hi -- I never saw an explanation for the writes that are occurring during ecpool reads. -- Tom > -----Original Message----- > From: Somnath Roy [mailto:Somnath.Roy@xxxxxxxxxxx] > Sent: Wednesday, May 13, 2015 6:48 PM > To: Deneau, Tom; ceph-devel > Subject: RE: journal writes when running rados bench seq on ec pool > > 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@xxxxxxxxxxxxxxx [mailto:ceph-devel- > owner@xxxxxxxxxxxxxxx] 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. > > -- Tom Deneau > > > > -- > 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 > > ________________________________ > > PLEASE NOTE: The information contained in this electronic mail message is > intended only for the use of the designated recipient(s) named above. If the > reader of this message is not the intended recipient, you are hereby notified > that you have received this message in error and that any review, > dissemination, distribution, or copying of this message is strictly > prohibited. If you have received this communication in error, please notify > the sender by telephone or e-mail (as shown above) immediately and destroy > any and all copies of this message in your possession (whether hard copies or > electronically stored copies). -- 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
