DAS to SAN Oversimplified
December 1st, 2009The majority of customers I work with today do not have centralized storage, a SAN, today. The customers environment looks like Figure 1 below, which we refer to as Direct Attached Storage, or DAS. You have a number of servers that have internal disk and at least a single NIC that connects the server to the LAN. My post below discusses performance and capacity concerns when you have servers running DAS.
Figure 1
In moving to a SAN your servers have 2 more additional NICs that will connect to dedicated Gigabit Ethernet Switches and also connect to your EqualLogic PS Series Array. This creates a Highly Available SAN so you can lose a NIC, a cable, a switch, an EqualLogic Controller and your SAN is still up and running without downtime.
This is a SAN, your storage area network, that is dedicated to centralizing your storage. By creating a centralized pool of storage you are now able to provide performance and capacity “on the fly” to your applications. Figure 2 below is an example of what a SAN with an EqualLogic PS Series Array looks like.
Figure 2
Figure 3 below illustrates creating a Volume from an EqualLogic Storage Pool and connecting that to Server One as Drive E: and Drive F:. iSCSI is simply scsi/disk commands over gigabit Ethernet. Server One views Drive E: and Drive F: as local hard disks that you just placed into your physical server.
Figure 3
With EqualLogic PS Series Arrays, you can setup your SAN in under an hour which will give your servers and applications additional capacity and performance when needed without interruption or downtime.
