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NetBSD 6.1.5 - man page for lfs_cleanerd (netbsd section 8)

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LFS_CLEANERD(8) 		   BSD System Manager's Manual			  LFS_CLEANERD(8)

NAME
     lfs_cleanerd -- garbage collect a log-structured file system

SYNOPSIS
     lfs_cleanerd [-bcDdfmqs] [-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      Stay in the foreground, do not become a daemon process.  Does not print additional
	     debugging information (in contrast to -d).

     -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 seg-
	     ments' 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.

BSD					  August 6, 2009				      BSD
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