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
