Hey Robert, On 02-10-13 14:44, Robert van Leeuwen wrote: > Hi, > > I'm running a test setup with Ceph (dumpling) and Openstack (Grizzly) using libvirt to "patch" the ceph disk directly to the qemu instance. > I'm using SL6 with the patched qemu packages from the Ceph site (which the latest version is still cuttlefish): > http://www.ceph.com/packages/ceph-extras > > When I turn on client caching strange things start to happen: > I run filebench to test the performance. > During the filebench the virtual machine will have intermittently really slow network connections: > I'm talking here about ping reply's taking 30 SECONDS so effectively losing the network. > > This is what I set in the ceph client: > [client] > rbd cache = true > rbd cache writethrough until flush = true > > Anyone else noticed this behaviour before or have some troubleshooting tips? I noticed exactly the same thing when trying RBD-caching on libvirt for some KVM-instances (in combination with writeback-caching in libvirt/KVM, as recommended). Even with moderate disk-access, it did exactly what you described. Had to disable the caching again because of this. Using KVM 1.1.2 with libvirt 0.9.12, patched to auto-enable RBD-caching on RBD with "cache=writeback", which is how I used it. AFAIK, this patch made it into the later official versions. Haven't really started debugging this yet. Regards, Oliver _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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