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A partition of my drive becomes unreadable. My PC is configured to dual boot Mac OS El Capitan and Windows 10. So there is a drive having Win10 UEFI installed. I tried to set the Mac Time Machine drive to be the partition/drive of Win10. Time Machine prompted me the partition does not have enough space to do be a Time Machine drive. So I quite setting up the Time Machine drive. Then the Win 10 partition in NTFS becomes unreadable. The partition cannot be accessed in Mac. When I tried to boot Win10, it failed to start. I then install a Win 7 in another drive and find that the Win10 partition cannot be accessed. It looks the Time Machine in Mac has corrupted this NTFS partition.

In TestDrice, I chosen the drive having issue and select type as GPT as it is detected( wonder should choose Intel type instead?)
After Analyse, it shows:
Warning: the current number of heads per cylinder is 255
but the correct value may be 128.
You can use the Geometry menu to change this value.


Shall I change the value to 128 and if this can be changed back to 255 afterwards?

Merci!

Use TestDisk 7.1-WIP, it will not display this warning message useless for EFI GPT.

Hi I using EFI FPT type and the Quick Search shows below:

check_FAT: Unusual media descriptor (0xf0!=0xf8)
Warning: number of heads/cylinder mismatches 16 (FAT) != 255 (HD)
Warning: number of sectors per track mismatches 32 (FAT) != 63 (HD)
EFI System 40 409639 409600 [EFI System Partition]
check_FAT: Bad number of sectors per cluster
Mac HFS 9474092 17862701 8388610 [~?~?~?M-:D^A]


it is processing per cylinder and probably take more than 10 hrs to complete. will this recover the whole partition after Quick Analyse?
Thanks

cgrenier wrote:Use TestDisk 7.1-WIP, it will not display this warning message useless for EFI GPT.

For a fast check, choose Stop, Deeper Search, Stop. If you see your NTFS partition, set it to P(rimary). On next screen, choose Write, confirm, Quit and restart your computer.

Hi As shown in last post, can you show me if the partition can be recovered? Thanks!