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I have an issue where it appears that an external hard drive which had been formatted on a mac system was loaded as a drive in Windows. Windows is obviously unable to read the data and now the drive won't mount in the mac. It appears that Windows overwrote something concerning the drive's information on what filesystems and types it has on it.

Mac diskutility is unable to repair the drive and the partition is showing up in the utility as a FAT32.

Using an applexsoft utility, I am able to verify the data is still on this drive, but I'd rather not spend $100 to save these files (its not my hard drive anyways).

Is there a way I can use some UNIX commands to find out the partition information on the drive, back the raw data up on it, then restore the data back onto the drive after re-formatting it again?

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migrated from Jul 2 '12 at 0:55

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The relevant command is dd but you may have to fiddle with the options to get it to do what you want it to. – Harry Johnston Jul 2 '12 at 3:04
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Your problem is the partition table has been overwritten by Windows.

The solution is using Testdisk to rewrite the partition table. You will need time, a lot of time to Analyse the disk. I suggest using the Deeper scan. It always works with me always.

You can also boot up your Mac into your OSX installation disk and using Disk utility to repair, it did work with me once.

Additionally, you should install Paragon HFS for Windows to read Mac drives. You should also shrink some space (about 30MB) and add a FAT32 partition for Paragon HFS installation for any computer that using Windows and doesn't have Paragon HFS.

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I'm not disagreeing with you, but can you explain under what circumstances Windows would overwrite the partition table without also formatting the newly created partition? – Harry Johnston Jul 2 '12 at 8:47
It's like when you create, delete, format a partition, the partition table has to be modify, and Windows will make it his own way. This happen to me once when I created a Fat32 partition from a empty partition on a HDD with a HFS+ partition. The HFS+ partition is showing on the MAC but in Read-only mode. – Nam Phung Jul 2 '12 at 12:39
TestDisk was the answer. i had to do a deep analysis by first selecting "EFI GPT". It found the HFS+ partition and added back to the partition table. Thanks, Nam. – kjokay Jul 8 '12 at 0:00

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