To show you how to use iSCSI, we're using a two-drive Thecus N2200XXX NAS server, which runs a custom version of Linux with iSCSI support, and a desktop system running Windows 7 Ultimate. Any system running Windows will do when paired with a NAS that supports iSCSI (such as the excellent Iomega StorCenter PX6-300d).
Pros and Cons
I've already touched on some of the benefits of using iSCSI. As mentioned above, an iSCSI network target appears to a system as a local drive; therefore, not only can you format the iSCSI target with the host OS's file system, but you can also run applications that require local storage from the iSCSI volume instead. This flexibility is great for small businesses because many programs cannot run over shared networks, even if you're using mapped drive letters; iSCSI works around that issue.
For some workloads, iSCSI may also offer better performance. Although iSCSI improves PC performance in the enterprise by allowing large storage arrays to connect to client systems without the need for custom hardware or cabling (which can result in a huge cost savings), I'm going to focus on average consumers and desktop systems here. To prove that iSCSI can enhance your PC's performance, we ran some benchmarks on a testing unit; I'll show you the results on the next page.
Note, however, that using iSCSI has some drawbacks. While setup is not terribly difficult, configuring an iSCSI target and initiator is more involved than simply browsing to a shared network resource. Also, only one initiator should be connected to the iSCSI target at a time, to prevent possible data loss or corruption. In addition, assuming that you use a fast server and drives, performance may be limited by your network connection speed. A gigabit network connection (or better) is the optimal choice; with slower network connections, the potential benefits of iSCSI may be nullified.
Following are the steps necessary to set up a Thecus N2200XXX NAS server for use with iSCSI. The steps should be similar for other devices and servers as well. To see how everything works, click on each screenshot for a larger version.
Step 1: Log in to the NAS server's configuration menu, configure the RAID mode, and reserve some storage space for the eventual iSCSI volume. We used RAID 1 for redundancy with two 2TB drives, and split our setup right down the middle--dedicating half of the usable capacity to an EXT4 data share while leaving the other half unused. We would later configure the unused space for iSCSI purposes.