What to look for in an SSD
Mar 22, 2010, 3:53 GMT
Washington - You can buy a computer with the fastest processor, the most muscular graphics card, and the speediest RAM. But your computer's performance will still be throttled if you continue to use a conventional hard drive. That's why solid state disks (SSDs) are this year's most coveted upgrade. Venture into the world of SSDs, though, and you'll see a myriad of competitors - and have a lot of questions. What should you look for in an SSD? Read on to find out.
Q: The rpm ratings of magnetic hard drives are what I use to determine how fast they are. If I buy an SSDs, what should I pay attention to when it comes to speed?
A: First of all, even the slowest of contemporary SSDs will typically read and write data faster than mainstream hard disks, which rely upon rapidly spinning platters with magnetic surfaces. As you probably know, the speed at which those platters spin determines, in large part, how quickly data can be read from them and written to them. That rating is expressed in revolutions per minute (rpm), and today desktop drives that spin at 5400 or 7200 rpm are the norm, with some 10,000 rpm drives preferred by power users.
SSDs are made up of memory chips. There's nothing that spins, so rpm ratings are history. Instead, as with conventional system memory, the rates at which data can be written to and read from an SSD's memory chips are expressed in megabytes per second, usually abbreviated as MB/s. Look at the fine print on an SSD's packaging or online, and you should see two MB/s ratings: one for reading data from the disk and one for writing data to the disk.
Ordinarily SSDs can read data from their internal flash memory faster than they can write data to it. Today, read speeds are in the range of 135 to 260 MB/s. Write speeds range roughly from 35 to 190 MB/s. As you can see, the difference between the slowest SSDs and the fastest can be significant - at least on paper. In practice, however, you're likely to be so impressed with the speed difference of just about any SSD over your existing hard drive that you'll be happy even with an SSD that's slow relative to others.
Q: Are all SSDs equally reliable?
A: Theoretically SSDs should be very reliable, given that they contain no moving parts - unlike traditional drives, which contain delicate read-write heads floating just a hair's breadth above rapidly rotating platters. However, early reviews of SSDs often focused on the fact that the chips in solid state disks could 'wear out' over time, as the internal chips' life span was reduced with repeated writing of data that occurs with hard drives.
Manufacturers responded by incorporating 'wear leveling' technology, which ensured data was written evenly across all of the chips within a drive rather than just a few. Wear-leveling or not, reports of SSDs wearing out from overuse have been virtually nonexistent thus far. And recent studies of expected SSD longevity using various constant writing scenarios peg life expectancy of today's SSDs anywhere from 12.9 to over 50 years. If those estimates hold up, you're almost certain to outgrow the capacity of any SSD you buy today long before you wear it out.
Q: Why are some SSDs faster than others?
A: A primary differentiator of SSDs today lies in the controller technology, which handles data protection as well as writing, erasing, and wear leveling. In short, an SSD's controller is responsible for a great deal of critical activity, and some controllers simply perform better - and faster - than others. Many original SSD users complained of drives that would hang or pause temporarily or simply couldn't be counted on to run smoothly for an entire computing session - issues that were blamed squarely on controllers.
That's why you'll see many SSD manufacturers trumpeting the virtues of the controller technology they employ as much as any other feature of the drive. And not all manufacturers make their own controllers. In fact, most do not. Intel's SSD controller technology is used by several other SSD vendors. Along with new controllers from Samsung, Intel's are widely considered among the best.
Q: I'm interested in upgrading my notebook with an SSD. Can I expect to see better battery life after the upgrade?
A: The subject of power consumption and SSDs has been hotly debated in technology circles, primarily because some tests have shown that SSDs can give notebook users an extra 30 minutes or so of battery life per charge, while others concluded that SSDs offer no energy savings or even perform worse in this department than traditional hard drives. The different results typically stem from multiple factors: whether drives and SSDs were in a constantly active state, which SSDs were tested, and which notebooks.
For those less concerned with benchmarks than real-world results, =however, the consensus seems to be that at the worst, you'll notice no appreciable reduction in battery life by using a modern SSD, and the speed gain you achieve by using an SSD will more than make up for any degradation of battery life that you might experience.
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