Having It All

It used to be that the attributes "reliable," "inexpensive," and "high-performance" were mutually exclusive in the storage world. In fact, if you could describe a storage-related product as inexpensive, you could safely assume that it wasn't highly reliable or particularly fast. Customers who wanted high reliability and speedy performance needed to go SCSI, and SCSI devices were never inexpensive. Enterprising hardware developers attempted to remedy the situation by building IDE (aka ATA) RAID controllers and enclosures. However, the limitations of the ATA technology meant that the improvement in performance, although quantifiable, was less than compelling when balanced against the high price. With IT budgets being tight, the cost of SCSI devices has been a big problem, especially for small businesses. Although they might be able to justify using SCSI devices with servers, workstation and desktop users needed to be running critical, disk-intensive applications to warrant the cost of SCSI subsystems, especially if the applications needed a lot of online storage. The fact that SCSI disk capacities remain significantly smaller than those available in less expensive ATA devices made the decision to use SCSI even harder.

However, Serial ATA (SATA) is finally becoming the answer to disk-performance-versus-cost questions for people who have workstations or small servers. SATA, with its simple seven-wire cables that can be up to a meter long (versus parallel ATA's 40-wire, 40cm cables), 150MBps performance, high capacities (drives as large as 300GB are available), and extremely low cost (approximately $1 per gigabyte), seems like the answer to many storage needs.

Add the current generation of inexpensive SATA RAID adapters, which offload RAID management to an on-card processor and are available for just over $300, and you have the makings of the formerly impossible high-performance, high-availability, inexpensive disk subsystem. And venders are adding a lot of features to these inexpensive controller cards--Broadcom, for example, offers an adapter that supports on-board RAID and hot swapping for less than $400; for more information, see the first URL below. (I should mention that SATA cards without on-board RAID can cost less than $100.)

Maxtor recently introduced the first 300GB-capacity SATA drive. A member of the 7200rpm DiamondMax 10 family, the new drive has a 16MB on-board buffer and support for native command queuing. Combine some of these drives with one of the Broadcom controllers (which are available with up to 8 ports), and for a fraction of the cost of a comparable SCSI system, you could easily have a terabyte of fast, hotswappable, relatively inexpensive RAID 5 storage for demanding workstation applications or for small to midrange servers running disk-intensive applications.

And the impact of SATA doesn't stop there. Vendors of high-end Storage Area Networks (SANs) and Network Attached Storage (NAS) are offering SATA drives as a way to compete on price at the entry and midrange levels of their markets. Earlier this month, HP announced one of the first storage arrays to support either SCSI or SATA drives. In fact, one of the big events last week at HP World 2004 was the Serial Storage Experience, where vendors showcased their SATA products as well as products that use the much pricier Serial Attached SCSI (SAS) technology.

Serial storage technologies seem to be the future of storage, with SATA meeting the needs of small and midrange customers and SAS at the high end. Both are technologies with which IT administrators, especially those responsible for storage, should become familiar.

Speaking of HP World, the event's proceedings should soon be available online at the second URL below. The downloadable presentations offer quite a bit of useful information. The Storage track presentations are especially interesting, with topics ranging from cost-justifying SANs to building multivendor switched fabrics.

http://www.broadcom.com/products/product.php?product_id=BC4000

http://www.hpworld.com/conference/hpworld2004/about.html

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