Riding the SATA wave

InfoWorld’s recent review of SATA (Serial ATA) controllers concluded that those cards are ready for enterprise deployment, although there are differences among different vendors and models (infoworld.com/125). Can we say the same for SATA disk drives?

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The short answer is: It depends on the application you plan to support. SCSI and FC (Fibre Channel) are still the best bet for critical applications. But the exceptional capacity and low cost per megabyte make SATA — and parallel ATA — drives a more cost-effective choice for applications that, for example, perform online backups or store reference data.

In fact, major vendors such as EMC, StorageTek, and Network Appliance are deploying SATA or parallel ATA drives for those types of applications, so why shouldn’t you?

Putting SATA to the test

Most SATA drives are essentially similar to their parallel-interface siblings, designed to handle the less demanding requirements of desktops and small workgroup servers. Many of the drives tested in this review are best suited to these types of specific responsibilities.

Western Digital is the exception, being the only vendor (at review time) that has developed enterprise muscles for a SATA drive, the WD Raptor. But it’s important to remember that Western Digital is also the only vendor in the group that doesn’t offer a line of SCSI drives: The WD Raptor is Western Digital’s waving flag to attract more enterprise buyers.

When it comes to disk drives, the aspects that matter to a potential buyer are performance, capacity, reliability, and cost. I tested the drives’ performance from an enterprise-deployment perspective, using Iometer 2003.2.15 to simulate typical server loads and recording the number of I/O operations per second that each drive was able to sustain for each test.

I then used a second Iometer script to measure the maximum transfer rate. I ran each script for 2 minutes, excluding the first 6 seconds of activity, and recorded the final average results. To test performance under stress, the server-load simulation test involved different data transfer sizes, varying from 512 bytes to 64KB, discretely scaled according to a commonly accepted pattern for file-server load.

For each data transfer size, the script created a composite mix of random disk accesses,  splitting I/O operation between reads and writes with an 8-2 ratio. I also ran the 73GB Fujitsu MAS3735NP — a fast-performing SCSI 320 unit — through the same tests for comparison.

A glance at the server-load simulation results  shows that the four SATA drives tested — the Maxtor Diamond Max Plus 9, Western Digital WD Raptor, and Seagate Barracuda Serial ATA V and Barracuda 7200.7 — all have strengths in different areas. Choosing the right one for your particular needs will depend on which quality is at the top of your list: fast data transfers, server  performance, reliability, capacity, or cost.

Maxtor Diamond Max Plus 9: Capacity leader

Maxtor offers SATA versions of its Diamond Max Plus 9 in 60GB, 80GB, 120GB, 160GB, and 200GB sizes, easily satisfying just about any capacity demand. The Diamond Max Plus 9 mounts both legacy and SATA power connectors, which can save a hasty trip to the local computer shop to buy those (thankfully inexpensive) adapters.

The 200GB version I reviewed compares well with the Seagate Barracuda 7200.7 in transfer rate and price per MB. Although the Diamond Max Plus 9’s performance in our server simulation test was not especially exciting, its larger size can certainly come in handy when free drive slots are scarce. For example, you can add a terabyte of space to your server with only five Maxtor drives (Maxtor also announced a new 250GB capacity model just before press time).

If you need lots of space and good transfer rates, the Diamond Max Plus 9 should be your first choice.

Seagate Barracuda Serial ATA V: Old faithful

Seagate’s Barracuda SATA V is an older sibling of the newer Barracuda 7200.7 and comes in an 80GB capacity as well as the 120GB drive that I reviewed.

Interestingly, the SATA V is the only drive in the group with no circuitry exposed. In fact, a metallic plate completely covers the lower part of the drive, protecting its soft belly. This additional armor, coupled with the highest resistance to nonoperational shock of the group (a trait shared by the Barracuda 7200.7), makes Seagate’s SATA V less vulnerable to damage from mishandling.

The drive also has the best price/capacity index, but unfortunately, its transfer rate results are the lowest in the group, well behind the other competitors. This makes the unit less appealing for near-line storage use.

Nevertheless, the Barracuda SATA V is a good drive and a very affordable choice for its intended use: a workstation or small workgroup server. Stretching it beyond those uses will tax the transfer rate.

Seagate Barracuda 7200.7: Fast and flexible

Seagate calls the Barracuda 7200.7 its second-generation SATA drive. It sports 80GB for each platter and advanced SATA features such as command queuing. I reviewed a 160MB unit, but the 7200.7 also comes in 80MB and 120MB capacity models.

Unlike the SATA V, the 7200.7 doesn’t have a bottom plate to protect the drive electronics, but it lists the same nonoperational shock resistance specs: 63Gs during use and 350Gs when inactive. In our lot, only the WD360 has better operational shock resistance numbers at 65Gs.

In performance tests, the Barracuda 7200.7 scored better marks than any other 7,200rpm unit in this review. Moreover, its maximum transfer rate and price/capacity index ranked slightly better than that of the Maxtor drive, which makes the Barracuda 7200.7 a worthy choice for deployment in both near-line storage and small server projects.

Western Digital WD Raptor: Rivaling SCSI

The Western Digital WD Raptor defines a class of its own among SATA drives. This is the only SATA drive on the market that spins as fast as 10,000rpm — versus the other drives’ 7,200rpm — and has markedly lower average seek and latency time, which translates into better performance.

Offering only 36GB of nominal capacity, the Western Digital drive also has the highest price/capacity ratio. In spite of the high transfer rate, the small capacity makes the Raptor less appealing for near-line storage or other applications demanding high capacity. Forthcoming Western Digital models, such as the 250GB WD Caviar SE SATA drive, will compare better in that area.

A simple glance at our server-load simulation results shows that the Raptor ranks best in server load performance and price/performance index, stretching out toward the elite of high-performing SCSI drives.

If you plan to provide SATA storage for a busy server on a budget, the speedy WD Raptor, which also includes an impressive five-year warranty, is hard to beat. 

Making drive decisions

For applications where high capacity and transfer rate are what matters the most, such as disk-to-disk backups, the Seagate Barracuda 7200.7 and the Maxtor Diamond Max Plus 9 emerge as overall winners, although the exceptional 200GB capacity of the Maxtor drive squeezes more data in the same amount of server space.

But if you plan to support applications where quick response time is critical, watch your step. In fact, with the notable exception of Western Digital’s WD Raptor, the drives in this review offer unexciting server performance.

As the disk drive market continues to evolve, you will find more enterprise solutions that mingle SATA with other technologies and new standards (see "Looking ahead to Serial SCSI"). Don’t be confused: They are not interchangeable, and each drive technology has its own place in the enterprise.