[libvirt-users] libvirt with sanlock

Daniel P. Berrange berrange at redhat.com
Tue Mar 13 14:54:21 UTC 2012


On Tue, Mar 13, 2012 at 03:42:36PM +0100, Frido Roose wrote:
> Hello,
> 
> I configured libvirtd with the sanlock lock manager plugin:
> 
> # rpm -qa | egrep "libvirt-0|sanlock-[01]"
> libvirt-lock-sanlock-0.9.4-23.el6_2.4.x86_64
> sanlock-1.8-2.el6.x86_64
> libvirt-0.9.4-23.el6_2.4.x86_64
> 
> # egrep -v "^#|^$" /etc/libvirt/qemu-sanlock.conf
> auto_disk_leases = 1
> disk_lease_dir = "/var/lib/libvirt/sanlock"
> host_id = 4
> 
> # mount | grep sanlock
> /dev/mapper/kvm--shared-sanlock on /var/lib/libvirt/sanlock type gfs2
> (rw,noatime,hostdata=jid=0)
> 
> # cat /etc/sysconfig/sanlock
> SANLOCKOPTS="-R 1 -o 30"
> 
> I increased the sanlock io_timeout to 30 seconds (default = 10), because
> the sanlock dir is on a GFS2 volume and can be blocked for some time while
> fencing and journal recovery takes place.
> With the default sanlock io timeout, I get lease timeouts because IO is
> blocked:
>    Mar  5 15:37:14 raiti sanlock[5858]: 3318 s1 check_our_lease warning 79
> last_success 3239
>    Mar  5 15:37:15 raiti sanlock[5858]: 3319 s1 check_our_lease failed 80
> 
> So far, all fine, but when I restart sanlock and libvirtd, it takes about 2
> * 30 seconds = 1 minute before libvirtd is usable.  "virsh list" hangs
> during this time.  I can still live with that...
> But it gets worse after a reboot, when running a "virsh list" even takes a
> couple of minutes (like about 5 minutes) before it responds.  After this
> initial time, virsh is responding normally, so it looks like an
> initialization issue to me.
> 
> Is this a configuration issue, a bug, or expected behavior?

Each libvirtd instance has a lease that it owns. When restarting libvirtd
it tries to acquire this lease. I don't really understand why, but sanlock
sometimes has to wait a very long time between starting & completing its
lease acquisition.  You'll probably have to ask the sanlock developers for
an explanation of why


Daniel
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