What reasons are there for choosing the case-insensitive version of HFS+ when formatting the primary drive partition? Would case-sensitive not always be the best choice?


7 Answers 7


Use the default (case-insensitive) unless you both a) know what you're doing and b) you absolutely have to. There are several programs (Norton Antivirus comes to mind) that won't work properly on a case-sensitive file system.

HFS is, by default, case-insensitive but case-preserving (i.e. it doesn't care what you type for comparison purposes, but it will remember what you type).


One or other can break applications, case-insensitive is the default however. If you've been using case-insensitive without issues then there are no guarantees that a transition to case-sensitive will go well. Here's one example from the apple support pages:

...don’t assume your third-party software solutions work correctly with case sensitivity. Important: Case-sensitive names do not ignore Unicode ignorable characters. This means that a single directory can have several names that are considered equivalent using Unicode comparison rules, but they are considered distinct on a case-sensitive HFSX volume.

  • 1
    So what's the standard then? Case-insensitive?
    – Ian C.
    Feb 9, 2011 at 0:30
  • 8
    Case-insensitive is standard, and is almost always the better option.
    – Cajunluke
    Feb 9, 2011 at 0:34

There is a good reason to choose a case sensitive file system. If you are concerned by the quality and the security of the applications you run you might be interested by any early mechanism which may discriminate badly programmed applications.

An application which at one time create a file named conf and later try to open the same file with the name CONF is at least poorly written. This is just plain bad programming practice. This kind of application is filled with vulnerabilities with the same average probability all over its code length. This is a dangerous application.

This dangerous application will most probably crash on a case sensitive file system.

This dangerous application will not crash on a case insensitive file system.

(Some applications will crash on both, but we are not highly motivated to sort out these ones.)

Hence a case sensitive file system may be considered as a good tool to early detect and block poorly programmed applications.

On the other hand, this level of programming quality control is far from sufficient to ensure that you don't have any other vulnerability.

  • 1
    So basically you are saying that as a developer/tester one should use a case sensitive filesystem, and as a mere user a case insensitive one?
    – nohillside
    May 20, 2013 at 17:54
  • → Patrix: I would advise every user to use case sensitive filesystem. No need to discriminate users. Better fight poorly written applications which are the roots of all security vulnerabilities.
    – dan
    May 20, 2013 at 19:32
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    It doesn't help the user if he needs to use an application which expects filesystems to be case insensitive (Adobe still has issues there for instance).
    – nohillside
    May 20, 2013 at 19:33
  • 1
    → Patrix: how right you are "Adobe still has issues there". Meanwhile, Adobe is sometimes able to make applications which are cleanly programmed and which run without a glitch on nearly every OS on the marketplace (Adobe reader).
    – dan
    May 20, 2013 at 19:41

There are some significant applications that will not work correctly with case sensitive. And there's really no reason to do it. I'm assuming since you're asking that you really don't have a reason to do it. You're definitely better off not doing it unless you have a specific reason, and don't care that many applications don't work right with it.


One good reason to use case sensitive file system is using git repositories. Syncing them to the repo causes problems again and again, if not using case.

But I suggest adding another partition using HFS+ formatted case sensitive for such an application and link the directories you need to that partition. My system partition is still case insensitive not because I kwow why but just because I'm afraid.

  • Apparently there's nothing to fear. OS X will run fine on case-sensitive HFS+. Though some applications may not. And I agree: git is a very good reason to do this.
    – Ian C.
    Apr 14, 2016 at 15:26
  • This answer isn’t very helpful, because it is too vague. It would be improved if you gave a concrete example of what can go wrong. I have never encountered any git issues on macOS.
    – Chris Page
    Oct 5, 2018 at 22:34
  • @ChrisPage one example that comes to mind: when I clone the linux source on Mac case-insensitive APFS, I immediately see changed files where "what changed" is the file naming (uppercase to lowercase.) Git on mac can't seem to reconcile this - git reset --hard or git checkout [file] can't seem to make the working tree clean. Jan 22, 2019 at 18:55

Adobe Creative Cloud apps will not run on a case sensitive system, and can be a major problem


Adobe programs are infamous for not working on case-sensitive filesystems. Adobe says:

You cannot install Adobe products on a volume that uses a case-sensitive file system, such as HSFX (HFS+) or UFS. This limitation applies to both the startup drive as well as the drive onto which the software is installed.


Steam cannot be installed on case-sensitive filesystems either.

Steam does not currently support case sensitive filesystems or partitions.


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