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DESCRIPTION

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 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.