Starter SANs suit many needs

The SMB sector is poised to become the next big market for SANs. For vendors courting this market, the biggest challenge is that because SMBs typically lack specialized storage architects and administrators, building SANs from components is a tricky proposition for them.

To see how some of the major players are addressing this issue, I looked at SMB-friendly SAN offerings from Compellent, Dell/EMC, Dynamic Network Factory, Hewlett-Packard, IBM, iQstor, MPC, and Nexsan. Of the eight systems tested, three offer FC (Fibre Channel), three offer iSCSI (Internet SCSI), and two offer both forms of connectivity.

Although marketed to smaller shops, these are enterprise systems at their hearts -- with some capable of scaling to dozens or even hundreds of terabytes. Easy to set up and use, each system offers performance suitable for all but the most demanding, specialized applications. You might assume iSCSI wouldn’t offer performance on par with that provided by FC, and this would be true for iSCSI over Gigabit Ethernet as compared with a 2Gbps FC link. But iSCSI can run over 10 Gigabit Ethernet, and with the right hardware and software in place, that combination could easily outperform 4Gbps FC.

Similarly, although the systems tested use FC, SCSI, or SATA drives, a drive’s performance isn’t necessarily a good indicator of the overall performance of a SAN system. The storage processor, network interface, caching, HBA, and other components can affect performance just as much or more than drives do. In my tests of the eight systems, I found no startling differences in performance. Regardless of the type of interface or drive used, all proved more than capable of filling the bandwidth to the box.

Some people make an issue of the greater MTBF (mean time between failures) of FC and SCSI drives (1 million hours or more) when compared with those of SATA and ATA drives (400,000 hours or more). But even with a 400,000-hour MTBF, assuming an active life of five years (approximately 43,800 hours), it’s likely that a SATA drive would be replaced before it would fail, and it is capable of providing three times the capacity of an FC or SCSI drive at a quarter of the cost.

A complete FC SAN system includes HBAs, a switch or direct cable connection from server to storage, and the storage subsystem. Dell/EMC and HP provide complete kits with FC HBAs, switches, and storage arrays. These kits make the installation and configuration of a SAN simple -- no worrying about getting matching components or whether they will work together properly. Both the Dell/EMC and HP systems include easy installation and RAID management software that make it easy to get the systems running.

This is not to say the other systems are difficult to install. The days of having to input long identification strings before HBAs and storage arrays can communicate are past. All the FC systems were easily autodiscovered and configured, and the software included with each system provided easy configuration and management.