> On Tue, 10 Apr 2012 14:55:52 +0200 > (...) > > > > Can we put this state dir on a shared volume so that this state dir > > > > is common for all the front-ends serving the same content? Is is > > > > supposed to work and NFSv4 can merge its state with existing state > > > > on a shared disk? > > > > > > Not properly, no. nfsd expects to have complete control over that > > > directory. There's no locking or merging of the data there. A node will > > > also clean that directory out in some cases, and that will throw your > > > state tracking off. > > > > Thank you for information. > > > > Is there any (preferably simple) way to demonstrate that this does not > > work properly? E.g., if I share the same export through two or more > > NFSv4 front-ends that share the v4recovery directory, do I trigger > > problems with this tool > > http://nfsv4.bullopensource.org/tools/tests/locktest.php? > > Nope. It'll all work just great...until it doesn't. I don't have any > specific failure scenarios, but most of the problems will be issues > with state recovery when a server node is restarted. > > That may manifest in different ways -- problems reclaiming locks for > instance, or even silent data corruption depending on the application. > > For instance, a node might hand out a lock and the client release it, > after a server node reboots but before a client that really "owns" it > reclaims it. Depending on the application, that may cause serious > problems. Hi, I don't think a active/active NFS server is possible with /var/lib/nfs/v4recovery on a shared media. I think you will get into major trouble if two or more nodes access that directory at the same time. On the other hand an active/passive setup is quite easy. There are some HOWTOs on the internet. I like the one of linbit most: http://www.linbit.com/de/training/tech-guides/highly-available-nfs-with-drbd- and-pacemaker/ The guide provides a basic path to follow. You have to tune it according to which distribution you use. Not all distributions have the necessary features. See: leasetime, grace time, ... Greetings, -- Dr. Michael Schwartzkopff Guardinistr. 63 81375 München Tel: (0163) 172 50 98 Fax: (089) 620 304 13
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