Does a Solid State Drive need to be defragged? Will such HARM the SSD?

There is no more need to defrag an SSD than a mechanical hard drive ... and on a Mac, that's almost never. You have to keep in mind that OS X is not Windows. Fragmentation is not much of a problem in OS X, compared to Windows where it is a problem.

In fact, since defragging can involve a significant amount of writing, I'd say it's even more inadvisable on an SSD than on a mechanical hard drive. SSDs consist of flash memory and defragmentation causes wear by making large numbers of additional writes to the flash cells, which have a limited cycle life.

Access speed on memory is not the same as it is on a traditional hard drive. This is because all areas of flash memory is accessible at the same speed no matter where the data is written. On a traditional drive, the heads need to "hunt" accross all the platters and gather all the info before it's reconstructed into the data you're requesting. It's is this hunting delay that defragmentation was designed to fix. All areas of flash memory on the other hand have the same access path request. There is no outer or inner area like there is on a magnetic drive.

been covered here

https://discussions.apple.com/docs/DOC-4032

Leonardosanti wrote:

...Also, is Trim Enabler needed if "garbage collection" is provided by the SSD maker?

Also, is it necessary to let my MacBook Pro sit idle on the Startup Manager's screen after booting with the Option key pressed IF I WANT garbage collection to work?

While "Macs run hot" is a truism, I notice my Mac heats up quite a bit then, after about, say, ten minutes.

IS THIS HEATING UP DANGEROUS to machine or data???

Please help and advise.

sincerely, Leonardosanti

First, did the SSD come with the Mac or did you install it yourself? TRIM is enabled automatically but only for Apple SSD's.

Garbage collection is a process which cleans up the SSD's data blocks for re-use, but only "garbage" is collected, so to speak. Unlike a HD, an SSD controller doesn't know that a file has been simply deleted so that the space can be reused; it only knows about file changes. TRIM was introduced as an OS method to notify the controller that a deleted file's space is now free (i.e., garbage to be collected) for erasure and reuse. TRIM Enabler turns TRIM on for third party SSD's but causes problems if used with Yosemite.

As to heat, make sure that any ventilation slots are clear, which often means using the laptop on a hard surface rather than your lap. The fans in a Mac speed up to compensate for heat build up but you can install smcFanControl to speed them up yourself.