Originally posted by: obeseotron
Originally posted by: Markbnj
No way. You're just reading/writing the drive, moving blocks around. That's what it was designed to do .
Try rephrasing your statement with another mechanical object and ask yourself how much sense that makes. Driving is what cars are designed to do too, driving them more often makes them fail sooner. Just because it is what something is designed to do doesn't make it harmless, all mechanical systems wear out with use, even normal "what it's designed for" use.
That said, defragmenting itself increases the amount of work a drive has to do, but also has the effect of decreasing the amount of work to access your files normally because they are contiguous rather than fragmented. If you defragment on a reasonable schedule you probably increase the longevity of your system. Doing it like crazy is going to put more stress on the drive than will be saved by having defragmented files, so it's probably not a good idea.
You shouldn't take any of it too seriously, you aren't going to have any very strong impact on drive life one way or the other, and there are a lot of factors more important than how often you defragment that will influence the life of a drive.