|OCZ Agility MLC SSD OCZSSD2-1AGT120G|
|Reviews - Featured Reviews: Storage|
|Written by Olin Coles|
|Wednesday, 22 July 2009|
Page 15 of 16
SSD vs Hard Disk Drive
The only things standing in the way of widespread Solid State Drive (SSD) adoption is the capacity and price of Hard Disk Drive (HDD) devices. Because flash-based SSD technology costs more per gigabyte of capacity than tradition magnetic hard drives, the benefits of speed and input/output performance are often 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 its been formatted and used. A perfect example is Indilinx Barefoot-based SSDs, which suffers severely degraded performance when writing to 'dirty' flash NAND. The reason that all of this matters 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 costs forced consumer SSD prices lower in 2009, the price of solid state components has been on the rise during 2010. Nevertheless, SSDs continue to fill store shelves despite price or capacity, and there are a few Solid State Drive products now costing only $2.33 per gigabyte. Although the performance may justify the price, which is getting dangerously close to the $1.13 per gigabyte WD VelociRaptor hard drive, costs may still close some buyers out of the market. Price notwithstanding, the future is in SSD technology and the day when HDDs are obsolete is nearing; but there are still a few bumps in the road to navigate.