Is it true that an external hard drive, or an internal hard drive can be defraged ... and a SSD should never be defraged ?
What is the minimum cost of a low end SSD, and the cost of a mid priced SSD ?
SSDs cannot be defragged because they are not really hard drives with platters. Internal or external platter hard drives, the kind that make buzzing and whirring sounds, are okay to defragment.
The reason is instead of using an actual magnetic surface on spinning media, an SSD is a giant thumb drive, or essentially uses similar technology. This technology, by the way, goes back quite far to the old days of EPROMS and EEROMS. Using special substrates and materials, the drives are written to by changing the voltage to a higher level and read at the normal lower voltage. In the olden days, this technology was used to write, burn as it was called, EEROMS. These are Electronically Erasable Read-Only Memory. To write the data, the voltage was boosted to +12V, and the device would get very warm. The data was read though at the normal, at the time, +5V. These devices were very slow in the old days - like 40ms, or even fast ones at 29ms. Today's SSDs run at RAM speeds of 10ns, which is a lot faster on reads than a regular hard drive. Writing though is still slower because of the act of changing voltages and the process of burning the data into the substrate. Today, the same or similar technology is used in SSDs, except the voltage levels are a lot lower. They do, however, get warm and this is quite obvious if you touch them while running. Even thumbdrives, which use similar technology, get warm as well.
The problem with this technology, though getting much better more recently, is these devices can be burned just so many times before they form dead spots. These writes though are many hundreds of thousands, so there's little risk of this happening too soon. The problem with defragging is this is a continous process which will degrade the life of the device as it writes a lot of data all over it. Instead of defragging an SSD, there are special routines, which either come with the software supplied by the manufacturer, or built-into the newer versions of Windows which handle the data and do clean-up routines. These clean-up routines reallocate the data and mark the bad spots so they're not used again.
Keep in mind that like real hard drives, the devices are a lot bigger than what you purchased. This extra space is for bad-sector replacement. Eventually, however, these spots run out and the device is dead. The other issue too is once these devices die, that's it! Unlike a regular drive, unless it suffers from a controller failure can still be operational except with lower performance. Then even with a controller failure, the drive may be recovered by a data recovery company. With SSD's this is impossible as the electronic device is completely dead.
SSD prices have come down considerably over the past years with quality going up as the technology has gotten better. I've seen 250GB drives going for about $180 these days with some lower and some higher, depending upon the brand. Their cost is still higher than the equivalent-sized platter drive, but this is still new technology. A 4TB SSD, however, is still upward of $10,000 while the equivalent-sized drive is about $250 the last time I looked. Like anything these days, look on New Egg or similar parts site for the best prices.
John
