JFS is a 64-bit file system that has been created by IBM. JFS has a full-form “Journaled File System.” The initial version of JFS (also called JFS1) was developed for IBM’s AIX operating system and was released in 1990.
In 2001, IBM released JFS2 (the Enhanced Journaled File System), and a version of JFS that was compatible with the Linux operating system .
The ” journaled ” aspect of JFS means that such a file system takes care of the tracks of what changes have been made to a log file (or journal) in files and folders.
This log is used to backtrack some changes if an unexpected power failure or system crash occurs in a case, which prevents data from being corrupted.
For example, if a file is in a process such as is in move or delete, when a computer crashes, then that journal is used to restore the file to its last stable state.
In the absence of a journal, the file may be truncate, which makes it unreadable and also causes other file system errors.
These Enhanced Journaled File System (JFS2) are also very similar to JFS, but they support larger volumes and file sizes.
For example, if a hard disk is formatted with JFS then it can be up to the size of maximum one terabyte (TB), whereas a JFS2-formatted disk can be up to 32 TB.
JFS maximum file size is slightly less than 64 gigabytes (GB), while JFS2 supports file sizes up to 16 TB. This large file capacity is very important for storing large databases that are often contained in a single file.
NOTE: JFS2 supports AIX 5.1 and above. It is supported in Linux systems with ” jfsutils ” package installed.