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accidentally changed format of HDD

Posted: 30 May 2018, 00:28
by 000masa000
Hello, I accidentally changed the format of my HFS+ external HDD to FAT32 with Apple Boot Camp Assistant as I was trying to make a bootable USB key with Windows 10 this evening. Now the 2 TB disk which has archived data I need to recover is reformatted as FAT32 and called WIN_INSTALL. I did not copy any data on to it (forced quit) and believe the 1.4 TB of original data is still there, but I am not sure the best way to find it again. I am running "Analyse" in the filesystem mode EFI/GPM assuming it needs to look for files under GUID partition map. Under FAT32 it only finds the empty disk. Can you please advise me the best way to recover the HFS+ format/files? Thanks you for the help. Marc Sabat

Re: accidentally changed format of HDD

Posted: 31 May 2018, 06:17
by cgrenier
If testdisk find an HFS+ partition after Quick Search or Deeper Search, set this partition as P(rimary), write the new partition table and after a reboot, try to access the data from a Mac.
If it doesn't work, it's always possible to use PhotoRec. Use the expert mode in Options, start the recovery and when asked, use a 512 bytes blocksize. Use the default options otherwise.
Good luck

Re: accidentally changed format of HDD

Posted: 07 Jun 2018, 00:18
by 000masa000
Hello, after four days analysing, testdisk did find the 2 HFS partitions (Recovery HD and my data partition), but after setting to primary, only Recovery HD mounts. Disk First Aid sees my old partition name, but it is greyed out and on attempting repair says

Invalid B-tree node size
The volume could not be verified completely
File system check exit code is 8
File system repair failed.

Is there any next step before running Photorec for a week to get a batch of files I need to sort through? I am so sure I haven't overwritten my disk, there must be some way to get the data off it. Argh!
thanks for your terrific software, wish I understood more clearly what to do!

thanks for any advice

Re: accidentally changed format of HDD

Posted: 07 Jun 2018, 06:15
by cgrenier
Unfortunately I have no solution except PhotoRec.