Thank you for the response. You are talking of median expected writes, but should I consider the single disk write speed or the network speed? A single disk is 100MB/s so 100*30=3000MB of journal for each osd? Or should I consider the network speed that is 1.25GB/s? Why 30 seconds? default flush frequency is 5 seconds. What do you mean with fine tuning spinning storage media? On which tuning are you referring to? Il giorno 09/lug/2013 23:45, "Andrey Korolyov" <and...@xdel.ru> ha scritto:
> On Wed, Jul 10, 2013 at 1:16 AM, Gandalf Corvotempesta > <gandalf.corvotempe...@gmail.com> wrote: > > Hi, > > i'm planning a new cluster on a 10GbE network. > > Each storage node will have a maximum of 12 SATA disks and 2 SSD as > journals. > > > > What do you suggest as journal size for each OSD? 5GB is enough? > > Should I just consider SATA writing speed when calculating journal > > size or also network speed? > > Hello, > > As many recommendations suggests before, you may set journal size > proportional to amount of median (or peak, if expected) writes > multiplied, say, by thirty seconds - that`s the safe area and you > should not able to suffer because of journal size following this > calculation. Twelve SATA disks in theory may have enough output to > thrash 10G network but you`ll face lack of IOPS times before almost > for sure, and OSD daemons are not working very close to the physical > limits speaking of transferring data from/to disk, so fine tuning of > spinning storage media still is primary target to play with in such > configuration. > > > _______________________________________________ > > ceph-users mailing list > > ceph-users@lists.ceph.com > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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