Doubling up on storage

Doubling up on storage

Two loosely related announcements grabbed my attention this week. Each introduces a new product that is a notable first-to-market for its manufacturer, but more importantly, these products mark a significant step up in storage. One technology doubles the disk drive capacity, while the other doubles the data transfer bandwidth.

At first blush, the capacity of Hitachi GST's (Global Storage Technologies) new Ultrastar 10K300 (300GB) may lead you to believe that this disk drive is yet another larger model parallel or serial ATA drive. But in reality this drive offers much more -- 2Gbps FC (Fibre Channel) and 320MBps SCSI connectivity. Clearly this drive was built to the same stringent criteria of reliability and performance as its sibling enterprise models. The obvious benefit to arrays built using these new large drives is a better capacity-per-square-foot ratio, which, for a short time, could compete with arrays built around the upcoming small-form-factor, 2.5-inch drives.

However, comparing its specs with the Ultrastar 15K73 reveals interesting differences beyond capacity and RPM (rotations per minute) values. For example, the 10K300 has slightly higher transfer rates and slower seek time, which together with its large capacity suggest it is best used for storing data that doesn’t call for subsecond response time.

Hitachi is not talking price at this time, so we won’t know how the new large models will affect the cost per gigabyte of storage until the first OEM ships arrays or servers with the new drives. And it depends on the vendor and the product. That could take six to eight months.

Nevertheless, it’s reasonable to assume that devices using 300GB drives will have a lower cost per megabyte than others using smaller models. Depending on how close that will be to ATA, the 10K300 could become an affordable alternative for applications such as disk-based backup and reference data storage.

Let’s move to the other news. LSI Logic has a new eight-port SATA (Serial ATA) controller -- the MegaRAID SATA 300-8X. From the 300 in the product name, I assume it stands for 300MBps, which indicates it’s based on the second version of SATA -- SATA II. The new version of the standard is on its way to full industry acceptance.

In addition to a double transfer rate, SATA II offers other crucial improvements over SATA I, including command queuing, which boosts performance; a port selector (dual-port, resilient path to devices), which is a reliability enhancer; and a couple of options designed to reduce manufacturing complexity, such as enclosure control and port multiplier.

Some of the features are self-explanatory, but let me emphasize that the port multiplier opens the possibility to channel multiple SATA device connections within a single cable, which assists in building neater enclosures and bridging to additional interfaces such as FC or Infiniband.

Back to LSI Logic, the MegaRAID SATA 300 doesn’t have a port selector, but all the other SATA II improvements are there, including a 300MBps max transfer rate on each port. For now, no SATA drive comes even close to that; therefore the card shouldn’t saturate its capacious aggregate transfer rate anytime soon.

Speaking of drives transfer rate, not long ago Hitachi made public some tests on 4Gbps FCAL (Fibre Channel arbitrated loop) devices. Although it’s too early to speak of products, developing a 4Gbps FCAL interface will eventually produce drives able to pump data at 400MBps on each port.

As you noticed, that’s another double for storage, which begs the question: Why is improving storage performance and capacity apparently so easy, while cost-conscious, effective management is still so difficult?

But that’s a topic for another column.

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