I know that it is necessary to keep ~15% free space on the system drive for proper function, but what about a non-OS drive that is used only for storage? My video archive drive never seems to get fragged, so I doubt that I will need freespace for defragging...any other reason to need it?
I'd guess the worst case scenario is that whatever defragging is done on that storage drive would slow down. At some extreme point (99% occupied?), it might not defrag at all. So what?
I've run even OS partitions beyond 90% full and never noticed any issues.
Since I installed Win 7 13 months ago, I have never done a manual defrag and have never seen more than 5% fragmentation on any drive---storage or OS.
You could turn off defrag on that storage drive and I'll bet never notice the difference.
I hope that you are right, because I will probably fill it up...or almost. 15% of a 1TB drive is ~144GBs, and that is more space than I want to lose.
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