FEBRUARY 2020 MACWORLD 125HOW TO CONVERT A CASE-
SENSITIVE MAC HFS+
PARTITION INTO A CASE-
INSENSITIVE ONE
Apple has long offered two versions of the
same HFS+ partition formatting scheme
used to create a filesystem for a Mac-
mountable volume: “Mac OS Extended
(Journaled)” and “Mac OS Extended (Case-
sensitive, Journaled)”. With the addition of
APFS formatting, that flavor
is also available in case
sensitive and insensitive
versions. What a
difference that “case-
sensitive” makes!
Case-sensitive
filesystems can allow
multiple files to have
the same human-
readable name using
different
capitalization. Blue
dolphin.pdf and
blue dolphin.pdf
and bLuE dOlPhIn.PDF are all
considered different items to a case-
sensitive filesystem. With the opposite, a
case-insensitive filesystem, the default
option for macOS in HFS+ and APFS,
those files can’t co-exist: They’re all
effectively the same name with a different
appearance.
In olden Unix days, case-sensitivity
made sense in some contexts, and Apple
offered a case-sensitive version of HFS+
for compatibility’s sake for those people
who required it.
However, some Mac software—notably
that made by Adobe and Valve—balks at
case sensitivity. I’ve heard from and read
of people who accidentally chose “case-
sensitive” when setting up a drive, not
realizing what they were getting
themselves into. They’d
like to shift off that into
the more standard
case-insensitive format.
While there was
software in the past
that could convert a
case-sensitive
partition to a case-
insensitive one in
place without
copying the data
off, the firm that
made that software
has shut down.
(Coriolis Systems was a long-time Mac
developer, and they generously made all
their software free on closing (go.
macworld.com/crls). However, the last
supported version of macOS is 10.13.
Because this involves filesystem-level
changes, I would not use this software
with 10.14 Mojave or later.)
Instead, you have to make a clone,