Not true! ZFS also normalizes. However, while HFS+ normalizes on _create_ (bad), ZFS normalizes on lookup (good).
Specifically, ZFS has a normalization-preserving, normalization-insensitive behavior -- a lot like case-preserving but case-insensitive behavior, but for normalization forms rather than case.
The way this works is that there's a) a string comparison function that can provide normalization- and/or case-insensitive comparisons, b) a character-at-a-time normalization function of sorts used for directory hashing (since ZFS hashes directories).
This is much better than normalizing on create, which is destructive and obnoxious when the form you normalize to is not the more common form and you live in a sea of applications that don't do normalization.
> Not true! ZFS also normalizes. However, while HFS+ normalizes on _create_ (bad), ZFS normalizes on lookup (good).
That's not a question of being true or not but referring to different things. The distinction I was trying to make is that HFS+ will force every filename into NFD. With ZFS, the filename as received from the APIs should be the same byte sequence which was used to create it and that avoids an entire category of bugs where e.g. a program writes a file and fails to find it in a later readdir() call. As an example, Subversion and Git both had numerous bug reports over the years where it was impossible to simply checkout a repo containing a file which used a different normalization form.
Say you create a file with a name that has different NFC and NFD forms, and you create it with the NFC form. Then you go try to create it with the NFD form, well, if doing an exclusive create (O_EXCL) then you'll get EEXIST, else you'll open the existing file.
It normalizes on LOOKUP, not create. On create it preserves the original form. Think of this as like case-preserving/case-insensitive behavior, but for form rather than case.
Specifically, ZFS has a normalization-preserving, normalization-insensitive behavior -- a lot like case-preserving but case-insensitive behavior, but for normalization forms rather than case.
The way this works is that there's a) a string comparison function that can provide normalization- and/or case-insensitive comparisons, b) a character-at-a-time normalization function of sorts used for directory hashing (since ZFS hashes directories).
This is much better than normalizing on create, which is destructive and obnoxious when the form you normalize to is not the more common form and you live in a sea of applications that don't do normalization.