Apple APFS Compatibility?

I’m looking at upgrading to High Sierra, but I’m checking programs that might not be compatible with the new Apple File System. Is there anyone who has tested it or confirmed that Duplicati will work with the new APFS?

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I have not tried it, but since Duplicati accesses things on the file level (like most other applications) I would be very surprised if the change in filesystem breaks things.

Just as an FYI, it appears if existing drives are only converted to APFS if they are SSDs - Fusion drives and HDDs (and I assume hybrid-HDDs) are NOT converted.

Yes, I have both on my system but the SSD has the boot partition, so I’m assuming it’ll force me to convert when I upgrade.

I’ve also read some applications are going to have difficulty because of moving to a case sensitive filesystem.

I assumed Duplicati would not have any issues, but I thought I’d throw it out to see if anyone has done the beta testing with macOS while using Duplicati as well.

I did not know they changed to case-sensitive.

You can toggle this by setting the environment variable FILESYSTEM_CASE_SENSITIVE=true somewhere before starting Duplicati.

If it is not set, it defaults to false on MacOS and Windows, but true on Linux.

Once APFS is out and testable how hard would it be to change the default to true when an APFS drive is detected?

Actually, what happens if multiple drives (or mounts) are included in a Source in which some are case sensitive and some are not?

Very easy.

That is not currently supported, and would require that each path was “tagged” with a case-sensitive/case-insensitive information to avoid mixing the two.

If you have a case-sensitive FS and use case-insensitive backups, you would only get one of the files backed up, as one filename would “overwrite” the other.

If you have a case-insensitive FS and use case-sensitive backups, you potentially store the same file multiple times. This is not really a problem for the backups because of de-duplication, but it would look weird if you list the files in the backup.


@jfspa, I’m curious if you did your MacOS update yet and, if so, have you had any issues with APFS (particularly in the Duplicati area)?

Apparently, Apple is stil defaulting to case insensitivity in APFS. From APFS FAQs

  • APFS, like HFS+, is case-sensitive on iOS and is available in case-sensitive and case-insensitive variants on macOS, with case-insensitive being the default.

Other devs are probably facing issues with case normalisation, since that has been slightly changed from HFS+. Here are the relevant changes from the FAQs:

  • APFS preserves the normalization of the filename and uses hashes of the normalized form of the filename to provide normalization insensitivity, whereas HFS+ stores the normalized form of the filename on disk to provide normalization insensitivity.

  • While both filesystems expect filenames to be encoded in UTF-8, APFS stores filenames on disk in UTF-8 encoding, whereas HFS stores filenames on disk in UTF-16 encoding.

  • APFS doesn’t allow files to be created with filenames that contain unassigned codepoints in the Unicode 9.0 standard, whereas HFS+ does.

I upgraded and have had no issues with it. Everything works the same so far.

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