Add second ip address to an existing SQl 2008 failover clustering

Consider whether you really need hot failover. If you're worrying about price at the level of an entry level SAN then consider whether you really have a business case for that recovery model. How expensive is your downtime for an outage?

If the cost of an outage justifies the cost of a decent SAN, buy it and don't penny pinch. Otherwise, consider other failover models. If your downtime is not so valuable, you can probably tolerate a hot standby model where the database is replicated to another server with local disk. This takes longer to recover but does not need shared disk storage. If this works for you then you don't need a SAN and the local disk on the servers will probably be much cheaper.

Another option would be the secondhand market. You can get a re-certified second hand Clariion CX200 or CX300 (which would probably do what you're after) for just a few thousand dollars. Re-certified hardware qualifies for vendor support and can be purchased through various outfits such as www.berkcom.com or www.bltserv.com.

(Disclaimer: I have no affiliation with either vendor but am a satisfied customer of BLT Services. Berkcom was recommended to me when I needed something that BLT didn't have).

Just did this for a client. They had 16 Gigs on each node, with each instance using 8 Gigs. One instance was starving for more RAM, so we upped it to 12, with alerting setup to watch for a SQL restart and send out a message. In the event of a failover due to hardware failing they'd manually lower it until the hardware was fixed.