At Tue, 9 Aug 2011 11:27:54 +0100, Brian Candler wrote: > > On Tue, Aug 09, 2011 at 06:59:54PM +0900, MORITA Kazutaka wrote: > > > If an app wants to update a single block, will this require Sheepdog to > > > fetch an entire 4MB object, modify part of it, and write it back? > > > > The app sends only the data to be written, and the server daemon > > overwrites the existing object. The app doesn't fetch the entire > > object. > > Thank you. So it's just like a normal block write, and the issues are (a) > network latency, and (b) software latency and scheduling delays in the > gateway and object manager processes. > > network latency would exist in an iSCSI SAN environment anyway. > > I know very little about how Linux schedules KVM guests. Would it help to > run the sheep process with a negative 'nice' value? I'm not sure how it affect the performance results, sorry. Perhaps it would improve the performance, but we need tests to confirm that. Thanks, Kazutaka > > Regards, > > Brian. > -- > sheepdog mailing list > sheepdog at lists.wpkg.org > http://lists.wpkg.org/mailman/listinfo/sheepdog |