|Seagate Momentus-XT Solid State Hybrid Drive|
|Reviews - Featured Reviews: Storage|
|Written by Olin Coles|
|Monday, 24 May 2010|
Page 11 of 12
HDD vs Hybrid Drive vs SSD
It's been the same argument for over two years now: SSDs offer the best performance, but HDDs still offer the best capacity and price. Now that Solid State Hybrid drives are available, that argument changes. While the optimal blend of bandwidth speed, operational performance, storage capacity, and value has yet to be delivered, Seagate's Momentus-XT is an ultra-affordable start in the right direction. Admittedly, our benchmarks are a poor substitution for real-world user experience, and the Momentus-XT isn't designed to move large files at SSD speeds. Installed as a primary drive for notebook and value-conscious enthusiasts, the Seagate Momentus-XT Solid State Hybrid Drive delivers up to 500GB storage capacity while starting Windows and opening programs like an SSD.
The last days of old technology are always better than the first days of new technology. Never has this saying been more true than with the topic of storage technology, specifically in regard to the introduction of Solid State Drive technology a few years ago. The only things standing in the way of widespread Solid State Drive (SSD) adoption are high storage capacity and affordable price of Hard Disk Drive (HDD) devices. Because NAND flash-based SSD technology costs more per gigabyte of capacity than traditional magnetic hard drives, the benefits of immediate response time, transfer speeds, and operational input/output performance often get overlooked. Like most consumer products, it wasn't a question of how much improvement was evident in the new technology, it was price. I'll discuss product costs more in just a moment, but for now consider how each new series of SSD product employs greater performance than the one before it, convincing would-be consumers into waiting for the right time to buy.
There's also a gray area surrounding SSD performance benchmarks that has me concerned. You might not know this, but SSDs can be very temperamental towards the condition of their flash NAND. My experience testing dozens of Solid State Drives is that a freshly cleaned device (using an alignment tool) will always outperform the same device once it's been formatted and used. A perfect example are Indilinx Barefoot-based SSDs, which suffers severely degraded performance when writing to 'dirty' flash NAND. The reason that all of this will matter is simple: the performance results reported to consumers in product reviews (such as this one) often report the very best performance scores, and the process used to obtain these results is not applicable to real-world usage. This is where garbage collection techniques such as TRIM become important, so that end-users will experience the same performance levels as we do in our tests.
Garbage Collection (GC) is the current solution for keeping flash NAND in 'clean' condition, while maintaining optimal performance. Windows 7 offers native TRIM support, and most retail SSDs also include this special GC function or at least offer a firmware update that brings the drive up-to-date. For anyone using an Operating System or SSD that does not offer Garbage Collection functionality, you'll be using 'dirty' flash NAND modules and suffering sub-optimal performance for each write-to request. A few SSD manufacturers offers free tools to help restore peak-level performance by scheduling GC to 'clean' used NAND sectors, but these tools add excessive wear to the NAND the same way disk defragmenting tools would. SLC flash modules may resist wear much better than MLC counterparts, but come at the expense of increased production cost. The best solution is a more durable NAND module that offers long-lasting SLC benefits at the cost of MLC construction. Adoption is further stalled because keen consumers aware of this dilemma further continue their delay into the SSD market.
Getting back to price, the changes in cost per gigabyte have come as often as changes to the technology itself. At their inception, high-performance models such the 32GB MemoRight GT cost $33 per gigabyte while the entry-level 32GB Mtron MOBI 3000 sold for $14 per gigabyte. While an enjoyable decline in NAND component costs forced consumer SSD prices down low in 2009, the price of SSD products has been on the rise during 2010. Nevertheless, Solid State Drives continue to fill store shelves despite price or capacity, and there are a few SSD products now costing only $2.03 per gigabyte. Although the performance may justify the price, which is getting dangerously close to the $0.79 per gigabyte for the WD VelociRaptor hard drive, costs may still close some buyers out of the market. Price notwithstanding, the future is in SSD technology - or possibly a SSD hybrid - and the day when HDDs are obsolete is nearing.