Did you set read/write permissions to the cache pool? For example, in openstack i need to set read/write permission for cinder to be able to use the cache pool.
On 3 Feb 2016 17:25, "Udo Waechter" <root@xxxxxxxxx> 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.
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