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
