Although putting together a production-ready iSCSI SAN isn't as easy as you'd think, it's not rocket science. With proper planning and a pair of good switches, you can build an enterprise-class iSCSI SAN.
Howard Marks is founder and chief scientist at Networks Are Our Lives, a network design and consulting firm in Hoboken, N.J. Write to him at firstname.lastname@example.org.
» Direct-Attached Storage. You could keep adding more drives to each server that needs more storage, but you'll waste a lot of disk space allocating whole RAID arrays to servers. Plus, you won't be able to build clusters with more than two members and it'll run slower, too.
» Fibre Channel. Conventional Fibre Channel SAN technology has a few advantages over iSCSI, including speed (current Fibre Channel gear runs at 2 Gbps), low latency and a deterministic access protocol that essentially eliminates packet loss from bandwidth overruns. But Fibre Channel is expensive--switches and HBAs typically cost up to five times more than iSCSI alternatives. Add in Fibre Channel's steep learning curve and historical lack of full interoperability, and it's probably best left to the old hands.