Hi James, Can you post the contents of the hung task warning so we can see where it is stuck? Thanks! sage On Tue, 27 Aug 2013, James Dingwall wrote: > Hi, > > I am doing some experimentation with Ceph and Xen (on the same host) and I'm > experiencing some problems with the rbd device that I'm using as the block > device. My environment is: > > 2 node Ceph 0.67.2 cluster, 4x OSD (btrfs) and 1x mon > Xen 4.3.0 > Kernel 3.10.9 > > The domU I'm trying to build is from the Ubuntu 13.04 desktop release. When I > pass through the rbd (format 1 or 2) device as phy:/dev/rbd/rbd/ubuntu-test > then the domU has no problems reading data from it, the test I ran was: > > for i in $(seq 0 1023) ; do > dd if=/dev/xvda of=/dev/null bs=4k count=1024 skip=$(($i * 4)) > done > > However writing data causes the domU to hang while while i is still in single > figures but it doesn't seem consistent about the exact value. > for i in $(seq 0 1023) ; do > dd of=/dev/xvda of=/dev/zero bs=4k count=1024 seek=$(($i * 4)) > done > > eventually the kernel in the domU will print a hung task warning. I have > tried the domU as pv and hvm (with xen_platform_pci = 1 and 0) but have the > same behaviour in both cases. Once this state is triggered on the rbd device > then any interaction with it in dom0 will result in the same hang. I'm > assuming that there is some unfavourable interaction between ceph/rbd and > blkback but I haven't found anything in the dom0 logs so I would like to know > if anyone has some suggestions about where to start trying to hunt this down. > > Thanks, > James > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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