Hi Gregory, another interesting aspect for me is: How will a read-request for this block/sub-block (pending between journal and OSD) be satisfied (assuming the client will not cache) ? Will this read go to the journal or to the OSD ? Best Regards, -Dieter On Tue, Mar 05, 2013 at 05:33:13AM +0100, Xing Lin wrote: > Hi Gregory, > > Thanks for your reply. > > On 03/04/2013 09:55 AM, Gregory Farnum wrote: > > The "journal [min|max] sync interval" values specify how frequently > > the OSD's "FileStore" sends a sync to the disk. However, data is still > > written into the normal filesystem as it comes in, and the normal > > filesystem continues to schedule normal dirty data writeouts. This is > > good ? it means that when we do send a sync down you don't need to > > wait for all (30 seconds * 100MB/s) 3GB or whatever of data to go to > > disk before it's completed. > > I do not think I understand this well. When the writeahead journal mode > is in use, would you please explain what happens to a single 4M write > request? I assume that an entry in the journal will be created for this > write request and after this entry is flushed to the journal disk, Ceph > returns successful. There should be no IO to the osd's disk. All IOs are > supposed to go to the journal disk. At a later time, Ceph will start to > apply these changes to the normal filesystem by reading from the first > entry at which its previous synchronization stops. Finally, it will read > this entry and apply this write change to the normal file system. Could > you please point out where is wrong in my understanding? Thanks, > > >> >I am running 0.48.2. The related configuration is as follows. > > If you're starting up a new cluster I recommend upgrading to the > > bobtail series (.56.3) instead of using Argonaut ? it's got a number > > of enhancements you'll appreciate! > > Yeah, I would like to use bobtail series. However, I started to make > small changes with Argonaut (0.48) and had ported my changes once to > 0.48.2 when it was released. I think I am good to continue with it for > the moment. I may consider to port my changes to bobtail series at a > later time. Thanks, > > Xing > -- > 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 -- 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
