Wednesday, August 4, 2010

Enterprise Storage: Two 2.5" 600 GB Hard Drives Tested

The latest 2.5” hard drive generation ships with SAS 6Gb/s and delivers up to 600 GB of storage space, narrowing the gap with much larger 3.5" disks. Today we're comparing the latest 2.5" drives from Seagate and Toshiba to see if they're faster, too.
Seagate’s Savvio was the first 2.5” hard drive product for enterprise applications. Today, you can get 2.5” SAS drives from Hitachi, Seagate, and Toshiba, but only Seagate and Toshiba ship the latest 600 GB, 10 000 RPM models for mainstream enterprise applications.

Hard Drives? Aren’t SSDs Better?

Hard drives will remain with us for many years, not just because of higher capacities and certainly not because of stellar performance. A decent SSD can easily overtake most hard drives. However, performance is only one of several requirements for enterprise storage, and there are many reasons to favor hard drives over SSDs.

First and foremost, there still are no long term studies on the reliability of SSDs. While we doubt that reliability issues will suddenly plague SSDs, individual cells will likely start failing as wear leveling retreads the same memory cells over and over. The result would be somewhat erratic performance, making it difficult to manage high-availability solutions. Performance variance is already an issue because most SSD performance isn’t 100% predictable. This is not the case for hard drives. But as long as operating parameters remain stable, performance is predictable. Administrators should plan to account for performance variances with oversized SSD arrays.

This is where SAS hard drives like the Seagate Savvio 10K.4 and Toshiba’s MBF-series fit in. Both deliver solid, predictable performance based on SAS 6Gb/s interfaces that enable easy deployment and management in standardized storage solutions. We wanted to know which drive is the better option from a performance standpoint.

The first Savvio drive arrived in 2004, and it was still based on an Ultra320 SCSI interface. At that time, the 10 000 RPM Savvio provided as much throughput as notebook hard drives did two years ago. The second-generation Savvio 10K.2 and the first 15K.1 were already based on SAS at 3 Gb/s. The Savvio 15K.1 at 15 000 RPM in 2007 was good enough to receive our editor’s choice award. Only last year, we tested the Savvio 10K.3 (10 000 RPM) and 15K.2 (15 000 RPM) in a large enterprise hard drive roundup. Both of these drives were among the first enterprise products that implemented the faster SAS 6Gb/s interface. The Savvio 10K.3 was great at delivering high efficiency, while the 15K.2 dominated our I/O benchmarks. It's time to look at the latest Savvio offering, especially since fresh competition has arrived.

The Savvio 10K.4 is Seagate's forth generation, and if you realize that it took six years for four product updates, you see that the enterprise market is much more conservative than the mobile and desktop segments, where new products are launched once or twice each year. This latest Savvio spins at 10 000 RPM and is available at 450 GB and 600 GB capacities. Both drives utilize three platters to reach their capacity. Since the 450 GB model does not take advantage of the full recording area on each of its platters, the drive can deliver slightly improved access time and I/O results.

Both drives come with SATA 6Gb/s interfaces and 16 MB of cache memory. Seagate still offers a Fibre Channel version (4 Gb/s), and there are SAS models with built-in encryption (TCG-compliant controller required). Seagate boasts that the Savvio 10K.4 is the first enterprise drive to deliver two million hours MTBF (mean-time between failure). This is at least 20% more than usual in this field.

The drive remains relatively cool, literally, with a surface temperature of 60°C after 30 minutes of intensive operation. However, the Toshiba drive runs cooler. We measured an impressive peak throughput of more than 140 MB/s. But again, Toshiba comes out slightly on top.

Toshiba has been very active recently, especially since the takeover of Fujitsu’s hard drive business. The overlap in the 2.5” notebook space is probably less significant than the fact that Fujitsu’s enterprise drives were a strong asset. Fortunately for Toshiba, the results appear profitable, as the latest mainstream enterprise 2.5” hard drive, the MBF2600RC, delivers very solid performance.

The Toshiba drive has a specification list similar to Seagate's model: 10 000 RPM spindle speed (10 025 to be precise), 16 MB of cache memory, and a 6 Gb/s SAS interface. Toshiba offers the same 450 GB and 600 GB capacities, but you can also opt for 300 GB. The latter runs two, instead of three platters, which should decrease power consumption.

We looked at the 600 GB drive. An excellent 3.5 W idle power comes courtesy of Toshiba's enhanced power condition state. This technology dynamically reduces spindle speed when the drive is not in use. Our active idle test requires the drive to be instantly available, but since there is no noticeable delay upon access, we can’t say anything negative about this feature. This is probably why the drive runs as cool as it does. A 54°C (rather than 60°C) surface temperature is quite a difference, and it's mirrored by the low power consumption numbers at maximum throughput, 1080p video playback, and workstation I/O.

A quick look at the benchmark results shows us that aggressive power savings don’t come at the expense of performance, although this isn’t the fastest 2.5”, 10 000 RPM enterprise drive across the board. The MBF2600RC delivers the best throughput of all comparable drives, and it delivers better I/O performance than the Savvio 10K.4. This is because Seagate apparently hasn’t optimized the latest Savvio drive for I/O performance at all. I/O numbers are still higher on older Savvio 10K drives and the Fujitsu 300 GB 2.5” MDB2300RC. In the end, the low power consumption paired with strong performance ensures that Toshiba’s 600 GB drive delivers great power efficiency.

We use PCMark Vantage test less for everyday applicability and more for the sake of looking at possible performance differences due to varying workload types.

Power Consumption

Idle power is radically low on the new Toshiba MBF2600RC drive because the spindle slows down when the drive is idle. Otherwise, it wouldn't turn in results as conservative as it's turning in. Seagate looks worse, though that's not really true. The new Savvio 10K.4 still delivers very low idle power consumption compared to other 2.5” enterprise hard drives.

Delivering data at peak throughput takes a bit more power on the Seagate drive than on Toshiba’s product. This is disappointing, as the last Savvio 10K generations did better.

The 1080p video playback test isn't a typical enterprise workload, but it shows how much power is required if the drives have to deliver a continuous, limited stream of data. In this case, Toshiba again does better.

Power consumption at high workstation I/O activity triggers the highest power consumption numbers on the Toshiba drive. Seagate requires the same power here.


Performance per watt for streaming read workloads looks extremely good on the new Toshiba drive. It delivers high throughput, while maintaining relatively low power consumption.

Workstation efficiency is also better on the Toshiba drive because of its higher performance paired with equivalent power consumption relative to the Savvio 10K.4. However, other drives deliver better power efficiency in I/O-intensive workloads.

Although the wheels don’t turn as quickly in the enterprise space as they do for notebook and desktop class products, there's still significant progress from one product generation to the next. Seagate and Toshiba beat Hitachi to the 600 GB capacity point on 2.5” drives, and both have characteristics that qualify them for different scenarios.

First, let’s talk about performance. Neither drive competes well with other enterprise hard drives when it comes to I/O performance. SSDs aside, 15 000 RPM drives are much faster. However, we must advise against purchasing the Savvio 10K.4 if your applications involve much I/O activity. Using the default firmware, the Seagate drive shows hardly any optimization for I/O-intensive workloads. The Toshiba drive isn’t a racer either, but its I/O results are acceptable.

On throughput and application performance, the clear winner is Toshiba’s MBF2600RC. It delivers better results in most of our benchmarks. At the same time, the drive’s power consumption is well below the Savvio 10K.4's numbers. This isn't only because of the Toshiba drive’s variable spindle speed at idle, but the drive is slightly lower on power overall. This places Toshiba on top when it comes to power efficiency, as well. The drive wins our throughput and I/O performance per watt testing.

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