lfs_cleanerd —
garbage collect a log-structured file system
  
    | lfs_cleanerd | [ -bcDdfmqs] [-isegment-number] [-Jraw-device] [-lload-threshold] [-nnumber-of-segments] [-rreport-frequency] [-Ssemaphore-address] [-ttimeout] node | 
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 -ds give more detailed
      debugging information.
- -f
- Use filesystem idle time as the criterion for aggressive cleaning, instead
      of system load.
- -isegment-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.
- -Jraw device
- Specify the raw device that the cleaner is to work against rather than
      trying to figure it out from the mount point. This is mostly useful when
      the cleaner is compiled into
      rump_lfs(8) and the ATF
      test framework.
- -lload-threshold
- Clean more aggressively when the system load is below the given threshold.
      The default threshold is 0.2.
- -m
- Does nothing. This option is present for historical compatibility.
- -nnumber-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
      -bwas also given, pass this many segments' worth
      of blocks through a single call to lfs_markv.
- -q
- Quit after cleaning once.
- -rreport-frequency
- Give an efficiency report after every
      report-frequency times through the main loop.
- -Ssemaphore address
- When the cleaner code is compiled into
      rump_lfs(8) and the ATF
      frame work, this option allows for a synchronization semaphore to be
      specified. This option is not available in the stand-alone
      lfs_cleanerd.
- -s
- When cleaning the file system, send only a few blocks through lfs_markv at
      a time. Don't use this option.
- -ttimeout
- Poll the filesystem every timeout seconds, looking
      for opportunities to clean. The default is 300, that is, five minutes.
      Note that lfs_cleanerdwill be automatically
      awakened when the filesystem is active, so it is not usually necessary to
      set timeout to a low value.
Thelfs_cleanerd utility first appeared in
  4.4BSD.