[Linux-cluster] Re: writing to GFS from multiple JVM's concurrently

[Gordan Bobic]

Tajdar Siddiqui wrote:

> Yes, this test works fine on an ext3 filesystem.
> 
> The JVM's are on different nodes.
> 
> The files being written/read on the 2 JVM's are different (file-names). 
> Where does locking come into play here ?
>
 > A JVM is only reading the files it creates, so there is no cross.

Writing files to a directory requires a directory lock. This lock needs 
to be bounced back between the nodes. This will slow things down at the 
very least. If you can arrange your files/application so that the nodes 
are writing to separate directory trees, then that will undoubtedly give 
you better performance.

What version of GFS are you using? If GFS2, try GFS1. GFS2 isn't 
entirely stable yet.

Gordan