Hi Mark, >>Sorry I got behind at looking at your output last week. I've created a >>seekwatcher movie of your blktrace results here: >> >>http://nhm.ceph.com/movies/mailinglist-tests/alex-test-3.4.mpg how do you create seekwatcher movie from blktrace ? (I'd like to create them myself, seem good to debug) >>The results match up well with your iostat output. Peaks and valleys in >>the writes every couple of seconds. Low numbers of seeks, so probably >>not limited by the filestore (a quick "osd tell X bench" might confirm >>that). yet, i'm pretty sure that the limitation if not hardware. (each osd are 15k drive, handling around 10MB/S during the test, so I think it should be ok ^_^ ) how do you use "osd tell X bench" ? >>I'm wondering if you increase "filestore max sync interval" to something >>bigger (default is 5s) if you'd see somewhat different behavior. Maybe >>try something like 30s and see what happens? I have done test with 30s, that doesn't change nothing. I have try with filestore min sync interval = 29 + filestore max sync interval = 30 ----- Mail original ----- De: "Mark Nelson" <mark.nelson@xxxxxxxxxxx> À: "Alexandre DERUMIER" <aderumier@xxxxxxxxx> Cc: ceph-devel@xxxxxxxxxxxxxxx Envoyé: Lundi 18 Juin 2012 15:29:58 Objet: Re: iostat show constants write to osd disk with writeahead journal, normal behaviour ? On 6/18/12 7:34 AM, Alexandre DERUMIER wrote: > Hi, > > I'm doing test with rados bench, and I see constant writes to osd disks. > Is it the normal behaviour ? with write-ahead should write occur each 20-30 seconde ? > > > Cluster is > 3 nodes (ubuntu precise - glibc 2.14 - ceph 0.47.2) with each node 1 journal on tmpfs 8GB - 1 osd (xfs) on sas disk - 1 gigabit link > > > 8GB journal can handle easily 20s of write (1 gigabit link) > > [osd] > osd data = /srv/osd.$id > osd journal = /tmpfs/osd.$id.journal > osd journal size = 8000 > journal dio = false > filestore journal parallel = false > filestore journal writeahead = true > filestore fiemap = false > > > > > I have done tests with differents kernel (3.0,3.2,3.4) , differents filesystem (xfs,btrfs,ext4), forced journal mode to writeahead. > Bench were done write rados bench and fio. > > I always have constant write since the first second of bench start. > > Any idea ? Hi Alex, Sorry I got behind at looking at your output last week. I've created a seekwatcher movie of your blktrace results here: http://nhm.ceph.com/movies/mailinglist-tests/alex-test-3.4.mpg The results match up well with your iostat output. Peaks and valleys in the writes every couple of seconds. Low numbers of seeks, so probably not limited by the filestore (a quick "osd tell X bench" might confirm that). I'm wondering if you increase "filestore max sync interval" to something bigger (default is 5s) if you'd see somewhat different behavior. Maybe try something like 30s and see what happens? Mark -- -- Alexandre D erumier Ingénieur Système Fixe : 03 20 68 88 90 Fax : 03 20 68 90 81 45 Bvd du Général Leclerc 59100 Roubaix - France 12 rue Marivaux 75002 Paris - France -- 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
