HFSX Explained

Written by John Harris, Updated on October 12, 2023

HFSX

HFSX is a file system developed by Apple Inc. to replace the HFS (Hierarchical File System), which is the main file system used in Mac computers and various other PCs. The iPod digital media player also uses this file system.

HFSX file system is another version of HFS Plus. They are almost similar to HFS+ volumes, except that the HFS Wrapper, typical of HFS Plus volumes, will never surround them and they support case sensitivity for the names given to all the files and folders. These volumes are easily recognized by a value of HX in the signature field with two entries in the Volume Header.

Architecture of HFSX

In the HFSX file system, all the volumes are divided into sectors, i.e., logical blocks, with a size of each block being 512 bytes. These sectors are again grouped into allocation blocks that comprise one or more sectors. In HFSX, the number of allocation blocks depends on the total size of the partition. In HFSX, address allocation blocks use a larger value compared to HFS, i.e., 32 bits instead of 16 bits (it can access 232 allocation blocks rather than 216 allocation blocks available to HFS).

Structure of Typical HFSX Volume

Sectors 0 and 1 of the volume are similar to the boot blocks as in an HFS volume and these are part of the HFS wrapper.

  • Volume Header: Volume Header is contained in sector 2 and is well equivalent to the Master Directory Blocks in an HFS volume. It stores a wide range of files regarding volume itself i.e. the size of allocation blocks, and the locality of other volumes such as the Extent Overflow File or Catalog File.
  • Allocation Blocks: Lists of allocation blocks, that are in use, and the list of blocks, which are free, are keeping tracked by the Allocation File. In HFSX, each allocation block is symbolized by one bit i.e. a zero bit means the block is free and a one means the block is in use. In addition, the Allocation File can also vary in size and there is no restriction to store contiguously within a volume.
  • Catalog File: All records of files stored in the volume are contained in the Catalog file. A record in the HFS catalog file is 512 bytes in size but in HFSX catalog files are 4 KB in Mac OS and 8 KB in OS X. Fields in HFSX the size can differ according to the size of data they store.
  • The Catalog File is just like a B-tree that keeps a record of all allocation blocks that are allocated to each file as extents. A file recorded in Catalog File is competent to record about 8 extents for each fork of a file. Files that are used to other extents are recorded in the Extent Overflow File.

The Attribute File can store three types of 4 KB records, that are not similar such as:

  • Inline Data Attribute records- stores small features that are easily fitted in the record list itself.
  • Fork Data Attribute records- contain a reference to a maximum of eight extents that can store larger attributes.
  • Extension Attributes– used to expand a Fork Data Attribute record when its eight extent records are used previously.

Pros of HFSX

HFSX is compatible with different Operating Systems like Windows, macOS, and Unix-based Systems which support longer file names for the files and directories that use error detection and correction mechanisms which help in better data readability and integrity during read operations which ensures data safety.

However, they also lacked some advancements that included limited file system features like limited size and capacity which was insufficient for large files or storage requirements. Moreover, file systems like UDF (Universal Disk Format) became more prevalent over HFSX due to its better features.

Conclusion

HFSX was mostly used in optical storage devices such as CD-ROM and DVD-ROM. As you may know, the usage of optical storage devices has decreased significantly. Nowadays, almost all storage devices use flash storage with more advanced file systems like NTFS and HFS+, which are widely adopted for various storage devices. It's advisable to use more modern and widely supported file systems for storage and data management needs.

Complete Data Recovery Software

Why Choose Remo?

100% safeSecure

100% SatisfactionGuarantee

10 Million+Downloads

Free TechSupport

Live Chat24/7 Support

Top