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LFS_CLEANERD(8) NetBSD System Manager's Manual LFS_CLEANERD(8)
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lfs_cleanerd -- garbage collect a log-structured file system
lfs_cleanerd [-bcDdfmqs] [-i segment-number] [-J raw-device]
[-l load-threshhold] [-n number-of-segments]
[-r report-frequency] [-S semaphore-address] [-t timeout]
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
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
-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
-f Use filesystem idle time as the criterion for aggressive clean-
ing, instead of system load.
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.
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 compatibil-
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.
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
-s When cleaning the file system, send only a few blocks through
lfs_markv at a time. Don't use this option.
Poll the filesystem every timeout seconds, looking for opportuni-
ties 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.
lfs_bmapv(2), lfs_markv(2), lfs_segwait(2), mount_lfs(8), rump_lfs(8).
The lfs_cleanerd utility first appeared in 4.4BSD.
NetBSD 9.0 August 6, 2009 NetBSD 9.0