On Thu, Jun 23, 2011 at 01:26:02PM -0400, David Teigland wrote: > On Fri, Jun 17, 2011 at 01:38:21PM +0100, Daniel P. Berrange wrote: > > To make use of this capability the admin will need todo > > several tasks: > > > > - Mount an NFS volume (or other shared filesystem) > > on /var/lib/libvirt/sanlock > > - Configure 'host_id' in /etc/libvirt/qemu-sanlock.conf > > with a unique value for each host with the same NFS > > mount > > - Toggle the 'auto_disk_leases' parameter in qemu-sanlock.conf > > I guess the all hosts are expected to have a consistent libvirt > configuration also. Is there any suggested approach for doing that in an > ad hoc environment? Could you use the shared file system for that > somehow? If you are using the libvirt storage APIs (virsh pool-create, vol-create, etc), then you need to make sure you use the same XML on every host. You should also make sure the XML requests block device paths under /dev/disk/by-path/ which are stable across hosts & reboots, and not use the unstable /dev/sdXXX names. > > > + if ((rv = sanlock_direct_init(&ls, NULL, 0, driver->maxHosts, 0)) < 0) { > > + if ((rv = sanlock_direct_init(NULL, res, driver->maxHosts, driver->maxHosts, 0)) < 0) { > > You should use 0 as the third arg for sanlock_direct_init(). sanlock > names the third arg max_hosts and the fourth arg num_hosts. sanlock's > max_hosts is mostly useless and should always be 0 which will cause > sanlock to use the default of 2000. > > > +# Each additional host requires 1 sector of disk space, usually > > +# 512 bytes. The default is 64, and can be reduced if you don't > > +# have many hosts, or increased if you have more. > > +# > > +#max_hosts = 64 > > This becomes libvirt's maxHosts and sanlock's num_hosts. The default of > 64 seems fine. I'm struggling a bit with what to say in the comment. It > doesn't affect the amount of disk space allocated, and there's little > reason to ever make it smaller. I think the comment could just say to > increase it if there are more than 64 hosts. Originally I could have saved space, but now that sanlock mandates alignment of 1MB / 8MB, this benefit has gone. Is there in fact any compelling reason to allow either num_hosts or max_hosts to be configurable at all ? If not, then I'd just remove this and just hardcode the sanlock standard 2000. > > +# The unique ID for this host. > > +# > > +# IMPORTANT: *EVERY* host which can access the filesystem mounted > > +# at 'disk_lease_dir' *MUST* be given a different host ID. > > +# > > +# This parameter has no default and must be manually set if > > +# 'auto_disk_leases' is enabled > > +#host_id = 1 > > You could say the valid range of numbers here is 1 to the max_hosts value > above (64). Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list