How do the many solid state drives in the market stack up? We ran some benchmarks, and here are the results…
Solid state drives are nothing new. But until recently, large capacity drives were extremely rare outside of high performance servers and embedded industrial applications due to their astronomical cost. Fortunately, flash prices have dropped to the point where large capacity SSDs (big enough to store operating system + many applications) are within reach of enthusiasts.
Our article today focuses on flash-based solid state drives (hereafter referred to as SSDs for simplicity). Specifically, we will be looking at those in the 2.5″ form factor. SSDs are essentially many flash devices connected to and managed by a controller chip, which then presents this to the system as a typical storage device.
The Future of Storage?
Manufacturers have touted SSDs as the replacement for hard drives. While their per gigabyte cost has yet to drop to hard drive levels, they do offer several advantages that may well justify their higher price to those seeking a performance boost.
Firstly, SSDs boast extremely low (often near-instantaneous) seek times. Hard drives have to wait for the head to move to the correct position on the platter, while solid state drives have no moving parts to worry about. This benefits random read performance greatly.
A single solid state drive can also achieve speeds that would typically require multiple hard drives in a RAID array. SSDs achieve this by using a form of internal RAID 0, striping data across multiple flash chips (like the ones in the photo above) and then reading them in parallel.
Having no moving parts whatsoever, solid state drives also run noiselessly and are far less vulnerable to physical damage.
Unfortunately, SSDs are not quite the holy grail of storage (yet) – they do have several shortcomings.
Solid state drives’ seemingly incredible speeds only apply when it comes to large reads and writes. Despite the growing size of user files, most drive accesses are actually very small, and this is where SSDs can turn out to be no faster than hard drives. Some SSDs use a write cache to combine small writes, increasing performance to some extent.
The nature of NAND flash also causes SSDs to slow down over time as more and more data is written to it. This can happen in anything from weeks to months depending on how often the SSD is written to.
After thousands of erase-write cycles, flash memory eventually loses its ability to hold data. This is going to take at many years even under extreme usage conditions, which renders it nowhere near as significant as the above issue.