On Wed, Apr 9, 2014 at 8:03 AM, Christian Balzer <[email protected]> wrote: > > Hello, > > On Wed, 9 Apr 2014 07:31:53 -0700 Gregory Farnum wrote: > >> journal_max_write_bytes: the maximum amount of data the journal will >> try to write at once when it's coalescing multiple pending ops in the >> journal queue. >> journal_queue_max_bytes: the maximum amount of data allowed to be >> queued for journal writing. >> >> In particular, both of those are about how much is waiting to get into >> the durable journal, not waiting to get flushed out of it. > > Thanks a bundle for that clarification Greg. > > So the tunable to play with when trying to push the backing storage to its > throughput limits would be "filestore min sync interval" then? > > Or can something else cause the journal to be flushed long before it > becomes full?
The min and max sync intervals are the principle controls (and it will in general sync on the min interval), yes. It will also flush when it reaches half full (not entirely full) so that it can continue accepting incoming writes. The tradeoff with those sync intervals is that turning them up means the sync could take longer, and I think there are some impacts on applying writes to the filesystem, but I don't remember for sure. -Greg Software Engineer #42 @ http://inktank.com | http://ceph.com _______________________________________________ ceph-users mailing list [email protected] http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
