After recently reformatting, I installed Windows 8.1, leaving half my drive unallocated. I would like to install Ubuntu in that unallocated space. The common wisdom seems to be that it is necessary to disable Fast Startup in order to prevent data loss when using such a dual-boot setup.
However, my impression is that such risk occurs when one OS tries to write to a shared partition while the other is hibernated. If I do not have any shared partitions between the two OSs – that is, if Windows only ever accesses its own partition(s, including recovery) and Ubuntu only accesses its own partition, does this risk remain? Under such circumstance is there any other downside to keeping Fast Startup enabled?
Further, if this setup did involve a shared partition, does the danger remain even when mounting as read-only?
Best Answer
Short answer: Yes. But you must be aware of some things.
The file system will only be corrupted if the second OS you boot makes changes in any partition that was already mounted by the OS you initialy hiberneted or shutted down in Fast-Start boot mode.
Answer: No. The only fact of mounting the hibernated partition in write mode could cause data loss, but this will not happen if the second OS mount that partition in read-only mode. By the way you could also unmount a partition you want to shared with the second OS before hibernating the previous OS, of course that couldn`t be a system partition but it could be some Data-(music,series,photos,documents)-partition-like.
Note: Hibernating and Fast Start up option manage the same type of considerations. In some part are pretty much the same.