We are using NFS for Shared storage, Can we use linux nfslcok service to implement IO Fencing ?
2012/10/26 Steve Loughran <[email protected]> > > > On 25 October 2012 14:08, Todd Lipcon <[email protected]> wrote: > >> Hi Liu, >> >> Locks are not sufficient, because there is no way to enforce a lock in a >> distributed system without unbounded blocking. What you might be referring >> to is a lease, but leases are still problematic unless you can put bounds >> on the speed with which clocks progress on different machines, _and_ have >> strict guarantees on the way each node's scheduler works. With Linux and >> Java, the latter is tough. >> >> > on any OS running in any virtual environment, including EC2, time is > entirely unpredictable, just to make things worse. > > > On a single machine you can use file locking as the OS will know that the > process is dead and closes the file; other programs can attempt to open the > same file with exclusive locking -and, by getting the right failures, know > that something else has the file, hence the other process is live. Shared > NFS storage you need to mount with softlock set precisely to stop file > locks lasting until some lease has expired, because the on-host liveness > probes detect failure faster and want to react to it. > > > -Steve >
