iSCSI and ATA on the rise

Gartner analysts are talking up two storage developments that may drive a new wave of modularity and cost reduction in server selection and infrastructure design.

On the storage front, two technologies -- iSCSI and ATA (including Serial ATA or SATA) -- have turned significant corners in terms of their applicability to enterprise applications, analysts John Enck and Bob Passmore told attendees at the Gartner Symposium/ITxpo 2004 here.

According to Passmore, ATA has moved beyond its reputation as a desktop technology to become an enterprise-ready medium for information lifecycle management (ILM) applications such as hierarchical storage management (HSM). "We haven't seen any evidence that ATA drives are significantly less reliable than SCSI drives, as they were expected to be," said Passmore. "But they are significantly cheaper."

Although ATA drives have become faster, bigger, and more reliable (and can be strung together to build ATA-based RAID arrays), Passmore noted that their speed is still no match for SCSI drives. Passmore advised IT executives not to have any illusions about using ATA-drives for performance-bound database applications any time soon. However, Passmore noted that their dramatically lower cost makes them a viable form of recovery media when compared to the king of recovery media: tape.

"We've already seen ATA systems deployed as tape emulators," said Passmore. "ATA is a good primary recovery media where you may need to [quickly] recover something that's 30-90 days old. But for compliance situations where data must be saved for much longer, tape is still better."

In addition to ATA's newfound role in low-cost infrastructure architecture, Passmore and Enck said that iSCSI, although yet to be ratified by the IETF, should be considered a credible alternative to the entrenched technology for building storage area networks (SANs): Fibre Channel.

Whereas Fibre Channel-based SANs require specialized hardware, iSCSI works over Ethernet. iSCSI's dependence on networking technologies that most organizations already have in place can lead to a reduction in both complexity and cost. But iSCSI is far from a shoe-in. Passmore noted that the cost of deploying Fibre Channel, particularly the cost of the switches, has come down dramatically. Still, cconsidering that Microsoft has released drivers and that iSCSI is still far less expensive than Fibre Channel, Passmore remains optimistic. "For orphaned servers in the data center, it may not make sense to spend another $2,000 to $3,000 to include them on a Fibre Channel-based SAN. iSCSI may be a better fit."

Blade angle?
Gartner's Enck, who specializes on the server side, agreed that iSCSI presents some unique opportunities in the blade server space. With the advent of Ethernet-bound SCSI storage, implicit support of expensive interconnect technologies like Fibre Channel by the blade manufacturers is no longer necessary in order for a blade to get access to a SAN.

With most system blades now including on-board storage and iSCSI gaining acceptance, Enck thinks the next development will be diskless blades, which could prove to be a boon for server consolidation, provisioning, and cost reduction.