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Write Ahead Physical Block Logging (WAPBL) provides meta
data journaling for
file system
In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one larg ...
s in conjunction with
Fast File System Fast File System may refer to:
* Berkeley Fast File System, as used by the various BSD variants
* Amiga Fast File System
The Amiga Fast File System (abbreviated AFFS, or more commonly historically as FFS) is a file system used on the Amiga pe ...
(FFS) to accomplish rapid filesystem consistency after an unclean shutdown of the filesystem and better general use performance over regular FFS. With the journal,
fsck
The system utility fsck (''file system consistency check'') is a tool for checking the consistency of a file system in Unix and Unix-like operating systems, such as Linux, macOS, and FreeBSD. A similar command, CHKDSK, exists in Microsoft Windows ...
is no longer required at system boot; instead, the system can replay the journal in order to correct any inconsistencies in the filesystem if the system has been shut down in an unclean fashion.
History
WAPBL was initially committed into NetBSD in 2008, and first appeared with NetBSD 5.0 (2009).
With NetBSD 6.0 (2012), ''
soft updates
Soft updates is an approach to maintaining file system meta-data integrity in the event of a crash or power outage. Soft updates work by tracking and enforcing dependencies among updates to file system meta-data. Soft updates are an alternative t ...
'' (known as ''soft dependencies'' in NetBSD) was removed in favour of ''WAPBL''.
See also
*
Log-structured file system
A log-structured filesystem is a file system in which data and metadata are written sequentially to a circular buffer, called a log. The design was first proposed in 1988 by John K. Ousterhout and Fred Douglis and first implemented in 1992 by ...
*
Soft updates
Soft updates is an approach to maintaining file system meta-data integrity in the event of a crash or power outage. Soft updates work by tracking and enforcing dependencies among updates to file system meta-data. Soft updates are an alternative t ...
*
Unix File System
The Unix file system (UFS) is a family of file systems supported by many Unix and Unix-like operating systems. It is a distant descendant of the original filesystem used by Version 7 Unix.
Design
A UFS volume is composed of the following p ...
(UFS/FFS)
References
External links
*
*
*
Computer file systems
Disk file systems
NetBSD
Unix file system technology
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