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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.

-J raw 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.

-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 semaphore 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(8).

-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.