I have posted this in an Apple forum but my issue is still unresolved so I am trying this forum. I have an iMac running Sierra with Parallels 12 and Windows 10. Using Windows 10, I have formatted an external flash drive to FAT32 which can be read and written to by both Sierra and Windows 10. I now want to reformat this drive to OSX Extended (Journaled) but Sierra Disc Utility does not show the flash drive, and Windows 10 has no option to format in OSX formats. Can anyone suggest a method for making the flash drive show up in Sierra Disc Utility?
Hi MikeB9, please shut down your Windows 10 virtual machine or disconnect it from Devices(Mac menu bar) ->External devices to display it on Mac side/Disc Utility. Mac OS X can natively read/write HFS+, FAT32 and exFAT. For simple file transfers, just use a USB flash drive, formatted as FAT32. Windows cannot natively read/write to HFS+. Read/Write FAT32 from both native Windows and native Mac OS X but the maximum file size: 4GB. You can use exFAT format, it is very easy and the rate of speed is also high as compared to FAT32. Please check out this article for more information about the drive formats.
Thank you PaulChris - that seems to be the answer (just quit Window 10 and plug in the Flash Drive; this then shows in Disc Utility).