HFS+
Unknownfilesystem · also known as HFS+, Mac OS Extended, HFS Extended
Hierarchical File System Plus (also known as HFS+, Mac OS Extended or HFS Extended) is a file system developed by Apple Inc. as a successor to the Hierarchical File System (HFS) [fmt/1105]. The system was introduced in January 1998 with the release of Mac OS 8.1 and continued to be the primary file system on Apple operating systems starting with Mac OS X, as well as one of the primary file systems used by the iPod portable media player. It features improvements to HFS, such as a 32-bit file length field rather than 16-bit to allow for much longer files names and adds support for Unicode characters in file names up to 255 characters long, containing any characters in the Unicode repertoire (though there may be OS or API-specific restrictions on permittable characters). Journaling was added in 2003 and case-sensitive file names were introduced under the HFSX option. It was replaced with the Apple File System (APFS) released with macOS High Sierra in 2017.
Identify it
| Extensions | .img.dmg.toast |
|---|---|
| Signatures | 482b0004 at byte 1024 (Hierarchical File System Plus, sig n.1)48580005 at byte 1024 (Hierarchical File System Plus, sig n.2) |
| PRONOM | fmt/1742 |
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From Just Solve the File Format Problem (File Formats Wiki), PRONOM. Updated 2026-10-24.