lfs_cleanerd(8) - NetBSD Manual Pages

Command: Section: Arch: Collection:  
LFS_CLEANERD(8)         NetBSD System Manager's Manual         LFS_CLEANERD(8)


NAME
lfs_cleanerd -- garbage collect a log-structured file system
SYNOPSIS
lfs_cleanerd [-bcdfmqs] [-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 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 clean- ing, 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 compatibil- ity. -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 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.
SEE ALSO
lfs_bmapv(2), lfs_markv(2), lfs_segwait(2), mount_lfs(8)
HISTORY
The lfs_cleanerd utility first appeared in 4.4BSD. NetBSD 5.1 November 18, 2006 NetBSD 5.1
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