The Ethernet networks used by iSCSI SANs are slower than Fibre Channel, since they top out at 1Gbit/sec., compared with 4Gbit/sec. for the latest Fibre Channel hardware. But the performance gained by moving to a SAN from direct-attached storage is so great that many midsize businesses don't miss the speed of Fibre Channel.
However, data warehouses or multi¬media applications could slow down Ethernet networks because they move large blocks of data at the same time, Trainer says. For such applications, consider Fibre Channel SANs or at least putting the iSCSI SAN on a separate network segment.
Greg Schulz, an analyst at The StorageIO Group, questions whether the graphical management tools so useful for today's comparatively small SANs will still be effective "when you have to install 200 or 500 ports on a server."
Gartner analyst Roger Cox recommends that small and midsize businesses equip their servers with dual host bus adapters or interface cards, as well as dual switches and storage controllers, to ensure uptime if one fails.
Finally, analysts say, be sure your low-end SAN vendor provides virtualization capabilities that make it easy to combine your various physical SANs into one virtual pool of storage as your storage volume grows.
For many midsize companies still looking to move off of DAS, these concerns are down the road while the benefits are immediate. As Silberman says, "It's a great relief to get this massive amount of storage, at this kind of price and this kind of easy functionality."