# OS X question - large folder copy/backup

**URL:** <https://boards.straightdope.com/t/os-x-question-large-folder-copy-backup/767819>\
**Category:** Factual Questions\
**Created:** [October 7, 2016, 2:10am UTC](https://boards.straightdope.com/t/os-x-question-large-folder-copy-backup/767819 "2016-10-07T02:10:57Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![zombywoof](https://avatars.discourse-cdn.com/v4/letter/z/9e8a1a/32.png) [@zombywoof](https://boards.straightdope.com/u/zombywoof)\
**Post date:** [October 7, 2016, 2:10am UTC](https://boards.straightdope.com/t/os-x-question-large-folder-copy-backup/767819/1 "2016-10-07T02:10:57Z")

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I have a fairly large (~20GB) folder on my Mac which I regularly copy/back up to a USB thumb drive - is there a simple way to only copy/overwrite the files which are new/updated since the previous copy?

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**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\
**Post date:** [October 7, 2016, 2:31am UTC](https://boards.straightdope.com/t/os-x-question-large-folder-copy-backup/767819/2 "2016-10-07T02:31:11Z")

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> [@zombywoof](#):
>
> I have a fairly large (~20GB) folder on my Mac which I regularly copy/back up to a USB thumb drive - is there a simple way to only copy/overwrite the files which are new/updated since the previous copy?

Try a tool like [Download arRsync for Mac | MacUpdate](https://www.macupdate.com/app/mac/20983/arrsync). If you don’t like it, just search around for another “rsync GUI”.

Or if you’re willing to use the terminal, do this:

rsync -Phav /path/to/source/folder /path/to/usb/drive

[rsync](https://en.wikipedia.org/wiki/Rsync) is a built-in magical utility that will compare all files in the source and destinations and only transfer over the portions that changed. It can speed up this process by hundreds or thousands of times. It was some genius’s PhD thesis work and now it comes standard on every Mac and Linux installation.

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**Author:** ![zombywoof](https://avatars.discourse-cdn.com/v4/letter/z/9e8a1a/32.png) [@zombywoof](https://boards.straightdope.com/u/zombywoof)\
**Post date:** [October 7, 2016, 4:07am UTC](https://boards.straightdope.com/t/os-x-question-large-folder-copy-backup/767819/3 "2016-10-07T04:07:22Z")

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Thanks - I will be giving it a try!

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**Author:** ![coremelt](https://avatars.discourse-cdn.com/v4/letter/c/4491bb/32.png) [@coremelt](https://boards.straightdope.com/u/coremelt)\
**Post date:** [October 7, 2016, 5:48am UTC](https://boards.straightdope.com/t/os-x-question-large-folder-copy-backup/767819/4 "2016-10-07T05:48:55Z")

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I’m pretty sure you can also configure Time machine to do this. Exclude all other directories except the one you want and set the USB thumb drive as the time machine back up device. Should work.