[Lustre-discuss] supporting fcntl, byte-range file locking

Oleg Drokin Oleg.Drokin at Sun.COM
Tue May 13 16:01:03 PDT 2008


Hello!

On May 13, 2008, at 12:37 PM, Wei-keng Liao wrote:
> What versions of Lustre support fcntl for byte-range file locking?
> Attached is a test program extracted from ROMIO to test fcntl() for
> locking. It ran fine on some Lustre versions.

Certainly many versions, going far back to 1.2 and prior.
This functionality is disabled by default though.
To enable cluster-consistent fcntl locking you need to mount your lustre
fs on a client with -o flock option.
If you do not need cluster-consistency, you can mount with -o  
localflock,
it would only be consistent on local node of course, but much faster
(only useful for some stupid applications that just test the presence
without actually using the functionality, of course, or when no
cross-node flock interactions are expected otherwise).
This "disabled by default" case got into effect in 1.4.8, prior to that
if you do not use -o flock option, then only locally-consistent locking
is provided.

Bye,
     Oleg



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