Solid-state drives (SSDs) have been around for many years. Their high cost, however, has limited their deployment to special environments, such as the military, where their rugged, shock-resilient design, coupled with extremely fast performance, justifies the expense.
With SSDs emerging based on flash memory rather than RAM, the devices are becoming much more affordable. A sensible price gap still remains between SSDs and spinning drives, but increased interest in the technology from major vendors such as Seagate suggests that their still-limited popularity will improve over time.
One of the vendors who took an early dive in the SSD market was Imation, who early this year announced the Pro 7000, a family of SATA (Serial ATA) SSDs aimed at enterprise deployment.
Based on technology from MTRON, the Pro 7000 family includes 2.5-inch models with 16GB and 32GB of capacity and a 3.5-inch model with 16GB, 32GB, and 64GB of space. Suggested retail prices range from US$550 to $1700 depending on capacity, though Imation recently introduced a less expensive model that offers slightly lower performance and knocks a couple hundred dollars off the price of larger-capacity models.
Imation claims ambitious performance number for the Pro 7000 drives, with sustained reads munching data at 120MBps and writes that are not far behind at 90MBps -- hence, my eagerness to review these drives.
After testing the 64GB and 16GB models, I am convinced that SSDs are the best drives that lots of money can buy, but their price and some quirky technical issues can put a damper on even the most optimistic deployment project.
Welcome to Jurassic Park To add some spice to my evaluation, I chose a non-SSD drive to use as reference and on which to run the same tests. The ideal candidate in my eyes was the Western Digital VelociRaptor WD3000, a 300GB SATA drive that is the fastest in its class, spinning at 10,000 rpm. The drive has a 2.5-inch form factor, but is riveted to a 3.5-inch adaptor, the IcePack, which also works as a heat sink.
More on their form factor: The two 3.5-inch drives in this bake-off essentially have the same perimeter, but the 64GB Pro 7000 has a noticeably thinner profile, at 0.625 inch versus the full inch of the VelociRaptor. The extra space should leave enough room for good airflow inside a case with multiple SSD drives.
After selecting a worthy trio of fast opponents for the test, my next step was to find a suitable test system that would not impede good performance. Unfortunately, none of the machines in my lab seemed to have enough I/O bandwidth to keep up with my fast drives. You can read more in my blog, but in short, before upgrading to an SSD drive, make sure that your server can deliver -- or you could be disappointed.
In the end, to ensure I had more control over the chip sets and software I'd be using, I decided to build my own machine. I had to go through several motherboards before finally finding one that could squeeze all the performance from my SSD drives. I finally got the expected performance using the ASUS M2N-E, which mounts the Nividia nForce 570 Ultra chip set and six 3Gbps SATA ports.
I added an AMD Athlon dual-core CPU and, to make sure that paging would not be a problem, 4GB of memory. I completed the prep work with a clean install of Windows XP plus SP2 and all the updates on a separate drive.
I also installed Office 2003, Iometer, and other applications, but I will share more on that later. To simplify testing, I ran performance tests on all my drives in raw mode, in essence without a files system built on them.
Running Iometer produced some interesting and revealing results. The two SSDs from Imation produced virtually identical performance with results very close to what Imation declares for the Pro 7000 line. The 64GB drive hit 45,400 IOps for sequential writes and 144 for random. For sequential reads, it hit 77,899 IOps; for random, 16,508. Meanwhile, the 16GB drive achieved 45,226 IOps for sequential writes; 119 for random; 79,916 for sequential read and 17,793 for random.
Not surprisingly, even a fast-spinning drive such as the VelociRaptor doesn't compare well with them: 23,165 for write sequential; 511 for write random; 19,926 for read sequential; and 486 for read random. (You can view my results in table form.)
However, it's also interesting to note that, although SSD demonstrated better results for all read scripts, the VelociRaptor random writes were noticeably faster.
I ran another set of tests to measure sheer transfer rate on each drive. The results were consistent, with the two SSDs noticeably fast on reads; the 64GB drive performed at a transfer rate of 105MBps, and the 16GB drive reached 115. The VelociRaptor made a 92MBps transfer rate for reads.
Again, the VelociRaptor has to concede defeat on read transfer rate -- albeit not by much. Instead, it took its revenge on writes, hitting 100MBps, compared to 81MBps for the Pro 7000 64GB and 79MBps for the 16GB variant.
However dramatic the difference in those results may be, it was only after I made each of them on my boot drive that I had a better sense of how the drives' performances differ in a real-world condition.
Faster to boot? To ensure that the drives were identical in content, I cloned the OS and every application from the original boot drive using Apricorn EZ Update, a $49 package that includes all the software and the hardware to move your Windows OS from one drive to another without too much hassle.
I used Microsoft Bootvis to measure how fast my machines would boot with all three drives. A full boot took 78 seconds with the Pro 7000s and less than half second longer with the VelociRaptor -- nothing to get too excited about. Bootvis also recorded nearly identical times when resuming from Standby and Hibernate for the two drives.
However, using Microsoft Office on the Pro 7000 drives made me a believer in the power of SSD. With my stopwatch, I gathered some numbers: Excel started in a blink of an eye, less than one second on the Pro 7000. Notably, it took just a little longer on the VelociRaptor. I measured similar minuscule differences for other Office apps. Nevertheless, sheer numbers can't convey the feeling of smoothness and responsiveness that I had firing up Excel or Word from the Imation drives compared to the Western Digital.
Perhaps that feeling was accentuated by how much quieter my machine was when I booted from the Imation drives. The VelociRaptor, by contrast, emits a distinct chatter when in use that rises well above the murmur of the fans. In summary, it doesn't register with significant metrics, but running Office -- and any other application, for that matter -- was sensibly smoother on the SSDs.
The benefits of running Office on an SSD proved difficult to express in numbers. I expected, though, that I'd find some very measurable and well-defined performance differences among my drives, in favor of the SSDs, in my final two tests: a drive-wide search on files' content and a plain defragmentation of each drive.
The killer app for SSD Instead, after running the defrag, I had to register a tie because the clock stopped at just about the same 3-minute, 20-second mark for the three drives -- although the larger Pro 7000 finished a handful of seconds sooner. Again, all drives had identical content, being clones of the same original drive.
However, I found a significant performance difference in favor of the SSDs when running a search. I used the standard Windows Explorer search applet, setting the scope to the entire drive and scanning all file content for the same word. The two Imation drives completed the search in about 57 seconds, while it took the VelociRaptor more than twice as long to find the same results.
By the end of my review, it was absolutely clear that any of the three drives I tested would be a significant improvement over older drives. However, I don't have a simple answer to the main question: Are SSDs worth deploying? It depends on the applications you need to run and the criteria used to reach that conclusion.
It's hard to justify the purchase in terms of price/capacity ratio, for example. With a nominal capacity of 300GB, the VelociRaptor has the best ratio: You can find the drive sold at $350 per unit or less on the Internet.
Nevertheless, if fast search is your main challenge -- consider, for example, applications such as data classification and analysis -- the Pro 7000's nearly 3-to-1 performance advantage over the Western Digital drive can somewhat mitigate the stiff price difference.
There are other factors to consider as well. Both vendors bestow a generous five-year warranty on their products, which suggests confidence in the resilience of these remarkable drives. However, it's only fair to note that while the VelociRaptor is a new drive, SSD technology doesn't have a comparably long track record to match its rival.
It's also worth noting that Imation indicates one million hours MTBF (mean time between failure) for the Pro 7000, while the VelociRaptor claims 1.4 million hours.
Finally, there's the green factor: SSDs have no electric motor inside, which translates in a much lower wattage per unit. Some models I have examined running at full speed absorb half the electricity used by spinning drives, which can translate to lower energy consumption and longer battery life in laptops and other mobile devices. Moreover, SSDs generate much less heat , which means less work and, again, less power needed to keep the temperature within limits.
When drawing all conclusions, the VelociRaptor emerges as the winner of this comparison because it offers a harmonious blend of excellent performance in many areas at a reasonable price, elements that will attract admins looking to improve application responsiveness.
Although their high sticker price banished the two Imation drives from first place in this bake-off, this confrontation with the VelociRaptor -- probably the fastest conventional SATA drive at the moment -- proves that solid-state flash has an as-yet unrivaled contribution to make to reduce applications lag. The technology's high price is still a significant spoiler, but all planets seem aligned to predict a rosy and less expensive future.