Those who follow my blog will know that I recently upgraded my MacBook Pro (Revision G) to an Intel X25-M 160GB SATA Solid State Drive (the G2 revision). I did this for two reasons. Firstly, I was offered the drive at a significant discount (which was nice), and secondly, I have been eager to test a high-end consumer SSD to know if the outrageous performance reports online were true, or if all the early adopters we just trying to validate their purchase.
If you look back over the past twenty years of consumer computer hardware, we have seen unbelievable innovation and performance gains across nearly all components. I remember my first build, an Intel i486SX2 running at 33MHz, with a whopping 4MB RAM and no 3D graphics card insight (I think that was back in 1994, making me 10 at the time). When you compare this to the Apple Mac Pro of today, with 12 processing cores (each rocking in at 3GHz), up to 32GB RAM and the ability to run multiple 3D graphics cards simultaneously (each with their own dedicated 1GB RAM), things have certainly come a long way. However one component has seen significantly less innovation...the poor hard drive.
Yes, I can now buy a consumer SATA drive that spins at 10,000 RPM and offers 2TB of storage, however the basic design and mechanical principles remain very similar to the 350MB hard drive I purchased nearly two decades ago. Therefore although the chipset architecture, processor, RAM, graphics and I/O interfaces have all made significant leaps forward in performance, the hard drive has been on a more modest progression and over recent years has been the bottle neck in most consumer computers. People have tried different techniques to get around this issue, such as throwing large quantities of RAM at the machine in an attempt to avoid caching on the hard drive or setting-up RAID 0 to stripe data across multiple drives, which can then be read or written to simultaneously. Unfortunately all of these efforts have simply acted as short term solutions and what everyone has really been waiting for is the next generation of hard drive. Enter the Solid-State Drive!
A Solid-State Drive (SSD) has the same physical dimensions as a standard hard drive (available in 1.8, 2.5 and 3.5 inches), it also uses the same SATA interface, however the main difference is that SSDs use solid-state memory to store persistent data, instead of containing spinning disks and movable read/write heads like traditional hard drives. The fact that SSDs use microchips, and contain no moving parts results in some significant improvements over traditional hard drives, for example SSDs are typically less susceptible to physical shock, are quieter, and have greatly reduced access times and latency. I have done my best to compile a list of the key improvements over traditional hard drives which helps explain why SSDs can be looked at as the next generation of hard drive.
- Improved start-up time (including when coming out of sleep) as no "spin-up" is required.
- Fast random access, because there is no "seeking" motion, unlike with traditional hard drives that rely on rotating disk platters.
- Improved performance, as SSDs are random access by nature and can perform parallel reads on multiple sections of the drive. Traditional hard drives require seek time for each fragment (assuming a single head assembly).
- Low read latency (again due to fast RAM and no moving parts), resulting is improved boot and application launch times.
- Consistent read performance, as physical data location has no impact on the drive's ability to access it.
- Reduced impact of file fragmentation, due to the greatly improved read time.
- Silent operation due to no moving parts.
- Lower power consumption.
- High mechanical reliability, as the lack of moving parts reduce the risk of mechanical failure.
- Ability to endure extreme shock, high altitude, vibration and extremes of temperature.
- Immune to magnets.
- Reduced size and weight (when comparing like for like capacity with traditional hard drives).
- Reduced potential for irrecoverable data damage due to less frequent errors while writing to the drive.
Although the list of advantages for SSDs is impressive there are a few key disadvantages.
- The cost of an SSD is currently significantly higher than a traditional hard drive.
- Flash-memory drives have limited lifetimes and will eventually wear out. With that said, things are improving with each generation, as OEMs have wanted assurances that a user could write 20GB of data per day to an SSD and still have it last, guaranteed, for five years. Intel have aligned to this statement with their X25-M SSD - Source Anandtech.
- SSDs have a lower capacity then traditional hard drives, for example the current largest consumer SSD is 480GB, when compared to 2TB for traditional hard drives.
What about TRIM, I hear you ask. It was discovered after the first generation of SSDs hit the market that the way client operating systems (Windows, Mac, Linux) handle operations like deletes and formats (not communicating the involved sectors/pages to the storage medium) resulted in progressive performance degradation of write operations on SSDs. The real reason for this is that the majority of client operating systems were designed in a world where 99.9% of the market used traditional mechanical hard drives, as a result the operations were not optimised for SSDs. To get around this issue the industry released a standard known as TRIM, which allows an operating system to inform an SSD which blocks of data are no longer in use and therefore can be wiped internally. This seemed to have helped reduce the performance impact that was being witnessed over time with first generation SSDs. Unfortunately to take advantage of TRIM you need to have a compatible SSD and operating system. The majority of second generation consumer SSDs (such as the Intel X25-M G2) now support TRIM, but the same can't be said for operating systems. On the Windows side you will have to be running Windows 7 and if you are on a Mac then you are completely out of luck (including OS X 10.6.4). Apple have the option to add TRIM support with a software update, but up to now there have been no reports as to when (if) this will happen.
As I am a Mac user the burning question is how much difference TRIM actually makes? Unfortunately, after a lot of reading, the answer is still unclear. Some people report the degrade in performance, while others do not. Others have tried work arounds such as erasing the free space using the Mac OS X "Disk Utility", however as to whether this has a positive impact is again unclear. In my opinion the most important piece of information is that even if your SSD does degrade in performance over time, the benchmarks prove that it will always be significantly faster then fastest traditional hard drive.
Hopefully that helps you understand the advantages and disadvantages of Sold-State Drives. The next step for me is to begin testing my new Intel X25-M SSD. Watch this space for updates.
Friday, May 4, 2012 at 5:00PM | 
