On Fri, Jul 29, 2011 at 01:11:27PM -0400, J. Bruce Fields wrote: > On Thu, Jul 28, 2011 at 08:44:18PM +0200, Frank van Maarseveen wrote: > > The following two patches implement support for a per-mount NLM > > grace period. The first patch is a minor cleanup which pushes > > down locks_in_grace() calls into functions shared by NFS[234]. Two > > locks_in_grace() tests have been reordered to avoid duplicate calls at > > run-time (assuming gcc is smart enough). nlmsvc_grace_period is now a > > function instead of an unused variable. > > > > The second patch is the actual implementation. It is currently in use for > > a number of NFSv3 virtual servers on one physical machine running 2.6.39.3 > > where the virtualization is based on using different IPv4 addresses. > > Thanks, that is something we'd like to have working well. > > Off the top of my head: > - Do you have a plan for dealing with NFSv4? Not yet but I'm not aware of any additional issue there (I haven't used v4 yet). > - Do you need any more kernel changes to get this working? No. > - What about userspace changes? None except for scripting. Years ago I had to grab a random sm-notify to make it work. At that time (2.6.27) there was a different patch for fsid based grace times from Wendy Cheng. > - Do you support migrating/failing over virtual nfs service > between machines, and if so, how are you doing it? Migration basically works as follows: - Create a network block device on the source machine to access a new physical block device on the destination. - Shutdown the virtual server, create a RAID-1 device on top of the original block device and start the server for the resulting device. The mdadm command (v2.5.6, 2006) is something like: mdadm -B -ayes -n2 -l1 $md $localdev -b $bitmap --write-behind missing - Add the network block device to synchronize the destination: mdadm $md --add --write-mostly $nbd - When RAID-1 has synchronized then shutdown the virtual server on the source machine and start it on the destination, i.e. migrate its IP address. A virtual server IP address removal is always accompanied by a iptables -I OUTPUT -s $ADDR -j DROP because traffic can still be in-flight causing troubles (have seen ESTALE). Every virtual server has its own statd directory (and a private "state" file), basically maintained from /var/lib/nfs/*. Upon startup after a crash the latter must be saved before the standard rpc.statd/sm-notify get a chance to empty it. -- Frank -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
