Re: [fedora-virt] Problems with Rawhide VM on CentOS 6.2
On Sun, Apr 01, 2012 at 06:52:27PM +0200, Tim Niemueller wrote:
Hi all.
To test our robot software against the newest and shiniest compilers and
libs we have a rawhide VM. Today I noticed a very annoying problem
(after not using the VM for a while), but I'm not sure if it's on our
side or if I should file a bug.
The VM is frequently unable to access its root partition (using virtio
for this VM). SSH connection end with "broken pipe", if locally on the
machine trying to execute "dmesg" it only says "cannot find
/bin/dmesg".
In the time when the error appears until I loose the connection was once
able to do "cat /proc/kmsg" showing errors on /dev/vda. In the libvirt
log on the host (CentOS 6.2 using libvirtd and virt-manager) I see the
following entries popping up in these situations:
block I/O error in device 'drive-virtio-disk0': Permission denied (13)
SELinux' audit.log is quiet. And the VM runs, and sometimes I can work
on it for 30mins straight, sometimes not even for 30secs. Any idea what
might be causing this intermittent problem?
During investigation I noticed that the very same message appears every
now and then in other VM's logs as well. They are running CentOS 6.2,
and one is FreeBSD 9.0. But in those I do not see the broken connection
or "cannot find file" problems.
The VM's disks are logical volumes in the same volume group. The machine
is a Dual Xeon Quad-Core with a speedy RAID array hosting the VG.
Does someone have a similar problem, or can give ideas how to fix or
investigate, and if to file a bug, which component to target? I'm not
even sure if it's a CentOS or a rawhide thing, though I assume the latter...
Is the host RAID array using 4K sectors?
Look at the files in /sys/block/<device>/queue and compare with:
http://libguestfs.org/virt-alignment-scan.1.html#linux_host_block_and_i_o...
Secondly, attach a virtual serial port to the guest and boot it using
the kernel command line parameter: console=ttyS0,115200. Then take a
look at the boot messages.
Thirdly, look at /var/log/libvirt/qemu/*.log
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines. Supports shell scripting,
bindings from many languages. http://libguestfs.org