hello everyone
i regularly download large files totaling 3-4 GB. i download them to an external hd in the belief that doing so won't fragment my mac's hd.
i burn & then Trash them.

does doing this actually avoid fragmenting my mac's hd?

thank you!

In a word: no. To elaborate on that: your HD (boot volume) gets 'naturally' fragmented over time by regular use. The fact that you keep one of your activities out of your 'home brew' only stops (actually: minimizes) that one activity from contributing to the fragmentation. In this context you may also want to consider the fact that there are two types of fragmentation, that of the data on disk and that of the disk directory itself.

Btw, this natural fragmentation isn't necessarily all that much of an issue, but for a discussion of the topic see the thread Why Defrag - By MMT3 in our previous Forums incarnation.

thank you for your reply and the info on your link. i'm a bit surprised that always moving large chunks doesn't do that much harm. altho my surprised feeling may just be dizziness from reading about fragmentation. whew!

also files of that size don't even count for the problem.

Way back "in the day" when file fragmentation was an issue, there were two important factors at work:

1) users were running well near the limit of their HD's capacity all the time. it was considered very unusual for you to have less than 50% of your disk space used, so free space was distributed throughout the drive in small pieces, space almost immediately getting reused when a file was deleted.

2) the files being deleted were of a similar size. Since this was creating small "holes" of free space, the OS was often forced to break up files into several smaller pieces that would fit into the holes.

Since you are dealing with files over a gig in size, the hole you create when you delete it is massive, and likely anything you need to save will fit in it in a single piece, creating absolutely no fragmentation.