Apple released macOS High Sierra yesterday. Amongst other changes, High Sierra includes the new Apple File System (APFS), which replaces the decades old Hierarchical File System (HFS). When you install High Sierra, at least if your boot drive is a Solid State Drive (SSD), the file system is supposed to be automatically converted to APFS. Although Apple’s website says that FileVault encrypted drives will be automatically converted, it didn’t give any details.
I installed High Sierra on two of my systems last night. One was a 2012 MacBook Pro and the other was a 2010 Mac Mini. Both contain Crucial SSDs. Since they’re third-party SSDs I wasn’t sure if High Sierra would automatically convert them. I’m happy to report that both were converted automatically. I’m also happy to report that FileVault didn’t throw a wrench into the conversion. I was worried that converting a FileVault encrypted drive would require copying files from one encrypted container to a new encrypted container but that wasn’t necessary.
If you’re installing High Sierra on a FileVault encrypted drive, the conversion from HFS to APFS won’t take a noticeably greater amount of time.