[Linux-cluster] iscsi doubt

[Jeff Sturm]

________________________________

	From: linux-cluster-bounces at redhat.com
[mailto:linux-cluster-bounces at redhat.com] On Behalf Of ESGLinux
	Sent: Monday, April 20, 2009 12:56 PM
	To: linux clustering
	Subject: Re: [Linux-cluster] iscsi doubt
	
	I only want to share a directory in which one node writes at one
and when it fails the other node has the diretory mounted with the data
and can write to it.  

The ONLY safe way to do this with ext3 is to ensure the fs is mounted on
one node at a time.
 
That means:
 
- The failover node cannot have the ext3 fs mounted until a failover is
performed
- The failed node must not write to the fs after it fails (i.e. you
fence the node)
- Prior to failing back to the primary node, the failover node must
unmount the fs
 
I believe you can automate such a failover with rgmanager, but I have
not done so myself.

	 Before I have known about cluster my decission would been to
mount the shares with NFS. Now I want to be more sofisticated and want
to use cluster tools, so I thought to mount it with iSCSI instead of
NFS, but always with the ext3 as the underlying filesystem.  

 iSCSI isn't a cluster tool, it's a block-level storage protocol.  Using
iSCSI is neither necessary nor sufficient to implement a cluster.  You
can use other software such as DRBD to get the failover you describe.
 
Jeff
 
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