[Linux-cluster] iscsi doubt

[Gordan Bobic]

On Mon, 20 Apr 2009 18:18:22 +0200, ESGLinux <esggrupos at gmail.com> wrote:
> Hello,
> 
> first, thanks for your answer,
> 
> I suspected it but why can i do it with NFS. ?

Not sure I understand your question. NFS is a network file system like CIFS
specifically designed to be mounted from multiple clients simultaneously.
ext3 is only designed with a single accessor in mind.

> the nodes never are going to be active at the same time so I can mount
the
> shares via NFS. With NFS when I create a file in a share automatically i
> got it in the shared mounted by all the clients.

I still don't understand your question - that is what NFS is designed for.

> In this case I don´t need to write to the share concurrently
> 
> can be this configuration a problem?

No, it's fundamentally impossible. In order to have a FS that can be
mounted simultaneously from multiple nodes, it has to be aware of multiple
nodes accessing it, which means that it needs coherent caching. Local file
systems like ext3 don't have this. When one node writes to the ext3 file
system, the other node will have cached the inodes as they were originally,
and it won't bother hitting the disk to re-read the contents, it'll just
return what it already has cached. And almost certainly corrupt the file
system in the process.

You cannot have a shared ext3 volume with writing enabled. Period.

Gordan