Editing QNX4FS

{{short description|File system for operating systems}}
{{more citations needed|date=February 2024}}
'''QNX4FS''' is an extent-based [[file system]] used by the [[QNX|QNX4]] and QNX6 operating systems.

As the file system uses [[soft updates]], it remains consistent even after a [[power failure]], without using [[journaling file system|journaling]]. Instead, the writes are carefully ordered and flushed to [[hard disk|disk]] at appropriate intervals so that the on-disk structure always remains consistent, no matter if the operation is interrupted. However, unflushed changes to the file system  are nevertheless lost, as the [[Page cache|disk cache]] is typically stored in [[volatile memory]].

Another notable property of this file system is that its actual metadata, like [[inode]] information and disk bitmaps, are accessible in the same way as any other file on the file system (as <kbd>/.inodes</kbd> and <kbd>/.bitmap</kbd>, respectively).<ref name="Mike Cramers Garage e795">{{cite web | title=The QNX4 Filesystem | website=Mike Cramer's Garage | url=https://www.mikecramer.com/qnx/qnx_6.1_docs/neutrino/technotes/qnx4fs.html |date=June 1, 2001}}</ref> This is consistent with QNX's (in fact, [[Plan 9 from Bell Labs]]'s, or historically [[Unix philosophy|Unix]]'s) philosophy that "[[everything is a file]]".

==References==
{{reflist}}

==External links==
* {{official website|http://www.qnx.com}}

{{File systems}}

[[Category:BlackBerry]]
[[Category:Disk file systems]]

{{comp-sci-stub}}