Ah, I might have found the solution: https://www.mail-archive.com/ceph-users@xxxxxxxxxxxxxx/msg26441.html Add access to the Cache-tier for libvirt. I'll try that later. Talking about it sometimes really helps ;) Thanks, udo. On 02/03/2016 04:25 PM, Udo Waechter wrote: > Hello, > > I am experimenting with adding a SSD-Cache tier to my existing Ceph > 0.94.5 Cluster. > > Currently I have: > 10 OSDs on 5 hosts (spinning disks). > 2 OSDs on 1 host (SSDs) > > I have followed the cache tier docs: > http://docs.ceph.com/docs/master/rados/operations/cache-tiering/ > > 1st I created a new (spinning pool) and set up the SSDs as a cache tier. > All is fine. I can create/access images with rbd. > I can seed that it is used with "rados -p cache-pool ls" > > > Now, when I add a cache pool to my existing pools, for example the one > which hosts all my VM images all hell breaks loose. > > The VMs all get I/O end request errors and remount their filesystems R/O. > If I shut them down and try to start them again, they won't start, virsh > gives me an error "cannot read metadata header" (or something like that). > > Also, "rados -p cache-pool ls" hangs forewer. > > I have read here: > https://software.intel.com/en-us/blogs/2015/03/03/ceph-cache-tiering-introduction > that adding caches works on-the-fly. > > Is there a special trick to add cache to a running, pool under load > (which is not very high, though)? > > And what about the "osd tier add-cache <poolname> <poolname> <int>" > command? its supposed to add a cache to the 1st pool. I can't see this > be used in bost of the above links. > > Thanks very much, > udo. > > > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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