I think this would be better to be done outside of Ceph. It should be quite simple for whatever monitoring software you are using to pick up the disk failure to set the target_dirty_ratio to a very low value or change the actual caching mode. Doing it in Ceph would be complicated as you are then asking Ceph to decide when you are in an at risk scenario, ie would you want it to flush your cache after a quick service reload or node reboot? > -----Original Message----- > From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of > Mihai Gheorghe > Sent: 03 February 2016 16:57 > To: ceph-users <ceph-users@xxxxxxxxxxxxxx>; ceph-users <ceph- > users@xxxxxxxx> > Subject: Set cache tier pool forward state automatically! > > Hi, > > Is there a built in setting in ceph that would set the cache pool from > writeback to forward state automatically in case of an OSD fail from the pool? > > Let;s say the size of the cache pool is 2. If an OSD fails ceph blocks write to > the pool, making the VM that use this pool to be unaccesable. But an earlier > copy of the data is present on the cold storage pool prior to the last cache > flush. > > In this case, is it possible that when an OSD fails, the data on the cache pool > to be flushed onto the cold storage pool and set the forward flag > automatically on the cache pool? So that the VM can resume write to the > block device as soon as the cache is flushed from the pool and read/write > directly from the cold storage pool untill manual intervention on the cache > pool is done to fix it and set it back to writeback? > > This way we can get away with a pool size of 2 without worrying for too much > downtime! > > Hope i was explicit enough! _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
 |