Last night I did a full system backup. On a whim I quick-formatted both of the destination drives (an internal IDE drive and an external USB drive) so that they were absolutely clean when the backup began.

I figured that this would give me 100% non-fragmented files, but this is not the case. My defragger is chugging away as I write this and it will take it several hours to complete, as more than 20% of the files on the newly-formatted destination drives are fragmented.

Why did the files, being written sequentially to a clean, empty drive, end up fragmented? If it matters, when I reformatted the drives I enabled compression.

tanstaafl.