for anyone wondering about TRIM:
https://forums.macrumors.com/threads/712557/
Mechanical drives are able to overwrite data with virtually no performance penalty, which is why even after years of use, the performance doesn't seem to degrade. The situation is different with SSD's, though, due to how NAND flash works.
To give a brief explanation of why this is the case, picture simple fragmentation. As more and more data is written to various blocks on a storage device, anything to be deleted later from the same block isn't likely to take all of the data within the block with it. There may be a few 4K blocks that are part of an image, for example, and another few 4K blocks that are part of a Word document. If you delete that image, the remnants of the Word document remain.
After a certain amount of time, these blocks end up in a very cluttered state, which basically explains the reason of performance degradation. So then we have garbage collection schemes, which help in this area by occasionally removing all loose data in a certain block and moving it to a more convenient one. But that doesn't rid the issue of an SSD having to write more than a block's worth of data.
For that process to take place, the SSD must first purge the data in the block, then write the fresh data to it. Compare this to a mechanical drive which simply overwrites the old data. It's easy to spot why there would be a hit in performance on the SSD. That's where TRIM comes in.
Mechanical drives are able to overwrite data with virtually no performance penalty, which is why even after years of use, the performance doesn't seem to degrade. The situation is different with SSD's, though, due to how NAND flash works.
To give a brief explanation of why this is the case, picture simple fragmentation. As more and more data is written to various blocks on a storage device, anything to be deleted later from the same block isn't likely to take all of the data within the block with it. There may be a few 4K blocks that are part of an image, for example, and another few 4K blocks that are part of a Word document. If you delete that image, the remnants of the Word document remain.
After a certain amount of time, these blocks end up in a very cluttered state, which basically explains the reason of performance degradation. So then we have garbage collection schemes, which help in this area by occasionally removing all loose data in a certain block and moving it to a more convenient one. But that doesn't rid the issue of an SSD having to write more than a block's worth of data.
For that process to take place, the SSD must first purge the data in the block, then write the fresh data to it. Compare this to a mechanical drive which simply overwrites the old data. It's easy to spot why there would be a hit in performance on the SSD. That's where TRIM comes in.
am sure I'm not alone in having deleted an important file at some point in the past. There have been occasions where I haven't been able to get my data back, but other times, tools such as testdisk proved to be an absolute life-saver. There are few levels of relief as high as the one you get when you successfully recover that all-important file.
But on an SSD with TRIM enabled, if you delete a file (and subsequently empty the Recycle Bin / Trash), you're simply not going to get your data back. As far as I'm aware, even with forensics, the data recovery simply isn't going to be possible. Unlike mechanical hard drives, which hold data magnetically, all it takes for NAND to assuredly erase the data is that little command, and boom, gone.
from the thread link above:
to sum things up:
1. It is VITAL for SSD's to have some sort of feature to prevent fragmentation and write degradation as well as wearing out of the flash chips.
2. One way this is implemented is through TRIM. You can read more at wikipedia. Just search for TRIM.
3. TRIM is an established standard, but requires the OS to do the work.
4. A Better way of implementing some way to prevent write degradation is a Garbage collect feature. Both OCZ vertex and Corsair drives (rebranded samsung SSD's) support this.
5. The Samsung SSD's only do the garbage collect for NTFS file systems.
6. The OCZ drives do this for ALL filesystems.
7. as a Mac user, i would get the OCZ Mac edition drives because they have been TESTED by apple and approved. A lot of people say "its the same drive with a different sticker" and i talked to OCZ about this. They showed me the specs on their drives for the Mac and Normal versions of their drives.
It turns out they are NOT the same and should NOT be mistaken for the same. The OCZ Mac edition drives are 10MB/s SLOWER in both read and write due to The Journaled Format (HFS+) of Snow Leopard. What i mean by this (and OCZ tech support confirmed this) is that drive speeds have to be tuned with the OS and with extremely fast SSD's this causes some hanging. The speeds used in the Mac edition provide the best performance for apple machines.
ouch! How bad are we going to feel a year or two down the line when these things come down to earth and we over paid so much? I must admit that running the OS and Apps on a SSD would certainly be a noticeable speed increase, but can anyone justify the $1500 or so a 512GB SSD will cost? God that hurts.
