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I'm trying to learn more about magnetic hard drives and what is considered "too much" transfer on OSX. On windows of course, you have a defrag tool, but I'm curious as to whether there is down side to transferring a ton of files right away onto a freshly installed OS partition.

For example, let's say I have a backup drive that failed and became read-only. If one takes the time to transfer 65gb worth of files (in which thousands upon thousands of files are involved) does this "weight down the system" in terms of indexing, etc?

Thanks for any answer; I'm just mainly trying to educate myself in terms of this particular problem.

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up vote 5 down vote accepted

No amount of data-transfer is too much. The hardware obviously has a max i/o throughput but there's no need to try to avoid approaching this limit. The disc has a finite lifetime but writing once to a part of it's capacity isn't going to wear it out.

Loading any amount of data onto a new freshly formatted hard disk won't cause fragmentation. Fragmentation is caused by intermingled deletes and writes. Some filesystems are less susceptible to fragmentation than others anyway.

If you are worried about OSX spotlight trying to index files (for faster searching) whilst loading, you should be able to disable it until loading is finished.

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cool. yeah; i disabled spotlight straight away. i just use the CLI anyway. the delete/write combo is precisely what i am wondering about w/r/t to a backup being restored like this and then deleted off of the machine. it seems like a ton of storage is occupied then freed and i was curious about what happens behind the scenes there with allocation of zeroed space. – jml Nov 13 '10 at 23:59
There's a Wikipedia article on fragmentation which describes what happens behind the scenes. See also the article on Extents – RedGrittyBrick Nov 14 '10 at 0:07

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