On Wed, Jun 11, 2014 at 12:44 PM, Alexandre DERUMIER <aderum...@odiso.com> wrote: > Hi, > > I'm reading tiering doc here > http://ceph.com/docs/firefly/dev/cache-pool/ > > " > The hit_set_count and hit_set_period define how much time each HitSet should > cover, and how many such HitSets to store. Binning accesses over time allows > Ceph to independently determine whether an object was accessed at least once > and whether it was accessed more than once over some time period (“age” vs > “temperature”). Note that the longer the period and the higher the count the > more RAM will be consumed by the ceph-osd process. In particular, when the > agent is active to flush or evict cache objects, all hit_set_count HitSets > are loaded into RAM" > > about how much memory do we talk here ? any formula ? (nr object x ? )
We haven't really quantified that yet. In particular, it's going to depend on how many objects are accessed within a period; the OSD sizes them based on the previous access count and the false positive probability that you give it. -Greg Software Engineer #42 @ http://inktank.com | http://ceph.com _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
