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I have an 100Gb external HD with bunch of stuff that was originally formatted to windows XP. I now have a mac and want to re-format the external to work with my Mac but dont want to lose the valuable data already on the external drive. How do i do this without losing my information on the external. I dont have a windows computer any longer.

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Also, i can read but not write to the drive from my Mac. – Greg Nov 29 '12 at 20:42
Hi, welcome. Press 'alt' while booting up, and select the BOOTCAMP partition. – bZezzz Nov 29 '12 at 20:45
PS: Not Lion OS ? – bZezzz Nov 29 '12 at 20:46
Mac Version 10.6.8 – Greg Nov 29 '12 at 20:46
@bZezzz it's a data drive not an OS. He's asking how to save the data when reformatting not how to boot from it. – Chris Nava Nov 29 '12 at 21:11

100 GB isn't that much in a world where 1T drives are becoming commonplace. Given that you know you can read the data, I would just copy it to another drive that had space, then just do a normal format. Why risk an inplace conversion that you already worry might lose your data given that clearly, there's already something odd going on?

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Formatting a drive neccesarily involves losing the information already there.

I'm presuming that this drive is formatted in NTFS, since MacOS can read from it but can't write to it. If it were in something like Fat32, you wouldn't be having this problem.

I'm not a MacOS user so I have no first hand knowledge of this product, but a brief search shows that there is a free third-party driver to enable read/write to NTFS drives in MacOS:

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Or just make it native, although I have not tried this one myself: Macworld – nerdwaller Nov 29 '12 at 20:53

From your words, you have put new data on this formatted drive. That's to say, some or all of your data has been rewritten. Therefore, you cannot recover all of your data back now!

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