What Is a Hierarchical File System?

Hierarchical File System ( HFS ) is a file system developed by Apple Computer and used on Mac OS. Originally designed for floppy disks and hard disks, it can also be found on read-only media such as CD-ROM.

HFS first appeared on September 17, 1985, as

The layered file system divides a volume into many 512-byte "logical blocks". These logical blocks are grouped into "allocation blocks", which can contain one or more logical blocks depending on the size of the volume. HFS uses a 16-bit value for the address allocation block. The maximum number of allocation blocks is 65536.

The following five structures are required to form an HFS volume:

1. Logical blocks 0 and 1 of the volume are boot blocks , which contain system boot information. For example, the system name and shell (typically

   A computer's file system is a method of storing and organizing computer data, which makes it easy to access and find it. The file system uses abstract logical concepts of files and tree directories instead of using physical blocks such as hard disks and optical disks to use data blocks. Concept, users use the file system to save data without having to care about the data block where the data is actually stored on the hard disk (or CD), just remember the directory and file name of the file. Before writing new data, the user does not need to care about the block address on the hard disk not being used. The storage space management (allocation and release) function on the hard disk is automatically completed by the file system. The user only needs to remember which file the data is written to. in.

   File systems usually use storage devices such as hard disks and optical disks, and maintain the physical location of files in the device. However, in fact, the file system may only be an interface for accessing data. The actual data is provided through network protocols (such as NFS, SMB, 9P, etc.) or in memory, and there may not even be corresponding files (such as proc). File system).

   Strictly speaking, the file system is a set of abstract data types that implement operations such as data storage, hierarchical organization, access, and acquisition. ^[2]