LFS_CLEANERD(8)

NAME
lfs_cleanerd - garbage collect a log-structured file system

SYNOPSIS
lfs_cleanerd [-bcdfmqs] [-i segment-number] [-l load-threshhold] [-n number-of-segments] [-r report-frequency] [-t timeout] node

DESCRIPTION
The lfs_cleanerd command starts a daemon process which garbage-collects the log-structured file system residing at the point named by node in the global file system namespace. This command is normally executed by mount_lfs(8) when the log-structured file system is mounted. The daemon will exit within a few minutes of when the file system it was cleaning is unmounted.

Garbage collection on a log-structured file system is done by scanning the file system's segments for active, i.e. referenced, data and copying it to new segments. When all of the active data in a given segment has been copied to a new segment that segment can be marked as empty, thus reclaiming the space taken by the inactive data which was in it.

The following options are available:

-b  Use bytes written, rather than segments read, when determining how many segments to clean at once.

-c  Coalescing mode. For each live inode, check to see if it has too many blocks that are not contiguous, and if it does, rewrite it. After a single pass through the filesystem the cleaner will exit. This option has been reported to corrupt file data; do not use it.

-d  Run in debug mode. Do not become a daemon process, and print debugging information. More -d s give more detailed debugging information.

-f  Use filesystem idle time as the criterion for aggressive cleaning, instead of system load.

-i segment-number
    Invalidate the segment with segment number segment-number. This option is used by resize_lfs(8), and should not be specified on the command line.

-l load-threshhold
    Clean more aggressively when the system load is below the given threshhold. The default threshhold is 0.2.

-m  Does nothing. This option is present for historical compatibility.

-n number-of-segments
    Clean this number of segments at a time: that is, pass this many segments' blocks through a single call to lfs_markv, or, if -b was also given, pass this many segments' worth of blocks through a single call to lfs_markv.

-q  Quit after cleaning once.

-r report-frequency
    Give an efficiency report after every report-frequency times through the main loop.

-s  When cleaning the file system, send only a few blocks through lfs_markv at a time. Don't use this option.

-t timeout
    Poll the filesystem every timeout seconds, looking for opportunities to clean. The default is 300, that is, five minutes. Note that lfs_cleanerd will be automatically awakened when the filesystem is active, so it is not usually necessary to set timeout to a low value.

SEE ALSO
lfs_bmapv(2), lfs_markv(2), lfs_segwait(2), mount_lfs(8)

HISTORY
The lfs_cleanerd utility first appeared in 4.4BSD.