Originally Posted by takman79
Originally Posted by Sean Webster
You can use it. Just not on the SSD.
why is that?
No point in defragging a SSD.
Why you shouldn't defrag a SSD:
Basically a SSD never needs defragmenting because it doesn't matter where the data is on the drive, they have ~.1 access time to anywhere on the the SSD's NAND cells and is always the same. All defragging does to an ssd is reduce its life by moving the data around on the drive.
There is a difference in defragging a SSD vs a HDD.
With HDDs the OS knows where the data on the HDD. Defrag programs assume that LBA (Logical Block Addresses) are fixed to a specific physical point on the hard disk. for example, LBA=1 is next to LBA=2, which is in turn next to LBA=3, thus when you defrag, it moves adjusts the files locations on the disk's platters where they can be read sequentially to increase the speeds. This is not the case for SSDs as LBAs for flash pages change based on its wear leveling algorithm.
For SSDs since they have flash memory and have a controller that takes care of wear leveling, when you defrag, it is a waste of writes to the drive on the drive, the OS thinks it knows where it is, but it really does not. It simply tells the SSD to read and write the data over in a certain location, but the controller of the SSD actually tells the data where to go. So, the OS does not know how data is being mapped on the SSD, the controller maintains the OS's understanding of the LBA but keeps it own internal LBA map.
Fragmentation is not going to hurt a SSD's speed. As a matter of fact SSDs fragment data on purpose to increase performance through parallel access, fragmentation is a requirement for maximum SSD performance. SSD controllers use multiple channels (typically 8-10) to improve performance (like RAID 0). Fragmenting data helps to ensure best performance. Even if a file is stored in sequential blocks according to its LBA address (ie. the file is not fragmented according to the OS/defrag program), it might be sprawled across several flash chips.