ISCSI In Practice

Aside from requiring a network, the primary prerequisite for implementing iSCSI is an iSCSI server. We tested two solutions here: one software, and the other hardware. The software-based solution goes by the name of SANMelody, and comes from a company called DataCore. This software can be downloaded from the web as a 21-day trial version. To evaluate the hardware approach, we took a look at Adaptec's Storage Array iSA 1500, which counts as a full-fledged SAN-application.

Both solutions fulfill all requirements of iSCSI, making the storage space on the host system available to the client systems through iSCSI. A client system can be fitted with an Adaptec adapter, reducing the CPU load on the system (for example in workstations).

In principle, iSCSI can be used on a 100Mbit network, but there will be a noticeable slowdown compared to local drives. Gigabit Ethernet is the more sensible choice here, since it is unlikely to become a bottleneck even if a multiple-drive RAID 5 array is used. Bandwidth could become an issue with RAID 0 arrays, but it is rare that such a fast storage area would be accessed and fed over a network.

On the client side, an iSCSI initiator is needed. These are available for practically every operating system. A Google search with the keywords "Microsoft", "iSCSI" and "Initiator" should quickly yield a number of relevant results.

The next step is now to log on to the server using the server's IP address from within the initiator software. This can be configured to occur automatically upon system startup. The allocated drives on the server will then be available on that computer as physical drives; they can be used like local drives, complete with a drive letter in Windows Explorer and "My Computer".

The iSCSI protocol also allows for a packet encryption scheme based on IPsec, although this is not compulsory. Within Intranets, for example, there is not always a need for encryption, while the security issues involved in WAN connections make the option much more important there.