server cluster NAS

Hey guys,

I'm struggling to understand something about server clusters. Apparently, if i was to set up a 2 server cluster i should be using Network Attached Storage as well as the 2 servers. Now, i set up the servers with the relevant applications, configure the cluster manager with the 2 servers using 1 as the active server and the other as the passive failover.

What is the NAS for? I don't install anything on there right? the applications are installed on the servers. Let's imagine i use sql on the server. Is the sql database imaged onto the NAS?

Any help muchly appreciated

I read this article.
http://www.networkworld.com/news/2004/0426cluster.html

And the NAS can give you backup for that particular server as well as added hdd space it seems. Although there is nothing said about NAS in the article, I can see where it can be used that way. Probably a good IDEA to do it.

After all clustering is to allow us to do things without all the initial expense of the mainframe setup of old. If I read it right.

The database needs to be kept on shared storage -- that's how you get the failover with minimal downtime if one of the servers fails.

I haven't seen clustering done with network attached storage before, just shared SCSI enclosures or using a SAN.

All that said, a cluster isn't something I'd choose to implement again. The one I manage now ended up being so painful that we locked each app to one particular server and it now acts as two servers that just need special handling.