I thought I might post this here. I wrote to Perfect Disk, which is a disk defragmenting software about SSD defrag. Anyway here is the response I got about it,
Thanks for contacting support.
While SSD drives certainly provide a performance improvement over traditional electro-mechanical HDD drives, SSD drives also have some deficiencies – including slow erase/write speeds and life span concerns. While file fragmentation typically doesn’t affect SSD drive performance as it does for a traditional HDD drive, free space fragmentation results in slow writes and reduced life span for SSD drives.
A good article that discusses and provides some benchmarks showing that optimizing an SSD drive improves performance and extends an SSD's life span can be found at http://rtcmagazine.com/articles/view/101053
Some notable points from this article – which was written by Apacer, a company that produces industrial SSD solutions:
"Since the erase/write speed is slow compared to read, a write multiplication due to free space fragmentation can slow down I/O time severely."
To write a sector, the SSD controller needs to read and merge the data, then erase and write back a data block, which is bigger than a sector, called an "erase block." The size of the sector is 1 - 4MB, which is much bigger than the sector size. By consolidating free space, the process of transferring data between erase blocks can be reduced or eliminated.
"This means a well-designed defrag algorithm can extend an SSD’s life span."
For SSD drives, PerfectDisk provides a solution to maintain write speed and improve life span. PerfectDisk’s special SSD Optimization pass does as the article recommends – “devise a defrag strategy that will improve throughput while at the same time not incurring too many erase counts.“ It does this by specifically consolidating free space without attempting to defragment files and consolidating free space in a manner that reduces erase counts. SSD Optimize is included as a standard feature in all editions of PerfectDisk.
Any thoughts on that Scott?