Journaling file system
file system that keeps track of not yet committed changes in a data structure called a “journal” (usually a circular log); when a system crash or power failure occurs, such file systems can be recovered online faster with less corruption
A journaling file system is a file system that keeps track of changes not yet committed to the file system's main part by recording the goal of such changes in a data structure known as a "journal", which is usually a circular log. In the event of a system crash or power failure, such file systems can be brought back online more quickly with a lower likelihood of becoming corrupted.
Depending on the actual implementation, a journaling file system may only keep track of stored metadata, resulting in improved performance at the expense of increased possibility for data corruption. Alternatively, a journaling file system may track both stored data and related metadata, while some implementations allow selectable behavior in this regard.
History
In 1990 IBM introduced JFS in AIX 3.1 as one of the first UNIX commercial filesystems that implemented journaling. The next year the idea was popularized in a widely cited paper on log-structured file systems.
This was subsequently implemented in Microsoft's Windows NT's NTFS filesystem in 1993, in Apple's HFS Plus filesystem in 1998, and in Linux's ext3 filesystem in 2001.
Rationale
Updating file systems to reflect changes to files and directories usually requires many separate write operations. This makes it possible for an interruption (like a power failure or system crash) between writes to leave data structures in an invalid intermediate state.
For example, deleting a file on a Unix file system involves three steps:
Removing its directory entry.
This brief starts where responsible research should: with the source description of “Journaling file system” as file system that keeps track of not yet committed changes in a data structure called a “journal” (usually a circular log); when a system crash or power failure occurs, such file systems can be recovered online faster with less corruption. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the general reference register because the source frames it as file system that keeps track of not yet committed changes in a data structure called a “journal” (usually a circular log); when a system crash or power failure occurs, such file systems can be recovered online faster with less corruption. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Jul 23, 2026. The linked authority identifier is Q579047. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1990, 1993, 1998 and 2001.
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This entry incorporates text from “Journaling file system” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.