NEWFS_LFS(8)						    BSD System Manager's Manual 					      NEWFS_LFS(8)

NAME

     newfs_lfs -- construct a new LFS file system

SYNOPSIS

     newfs_lfs [newfs_lfs-options] special

DESCRIPTION

     newfs_lfs builds a log-structured file system on the specified special device basing its defaults on the information in the disk label.
     Before running newfs_lfs the disk must be labeled using disklabel(8), the proper fstype is 4.4LFS.  Reasonable values for the fsize, bsize,
     and sgs fields are 1024, 8192, and 7 respectively.

     The following options define the general layout policies.

     -A 	 Attempt to compute the appropriate segment size using the formula 4 * bandwidth * access time.  The disk is tested for twenty
		 seconds to discover its bandwidth and seek time.

     -B logical-segment-size
		 The logical segment size of the file system in bytes.	If not specified, the segment size is computed by left-shifting the parti-
		 tion label's block size by the amount indicated in the partition table's segshift.  If the disklabel indicates a zero block size
		 or segment shift, a compile-time default segment size of 1M is used.

     -b block-size
		 The block size of the file system in bytes.  If not specified, the block size is taken from the partition label, or if the parti-
		 tion label indicates 0, a compile-time default of 8K is used.

     -F 	 Force creation of an LFS even on a partition labeled as another type.	newfs_lfs will use compile-time default values for block
		 and fragment size, and segment shift, unless these are overridden by command-line flags.

     -f fragment-size
		 The fragment size of the file system in bytes.  If not specified, the fragment size is taken from the partition label, or if the
		 partition label indicates 0, a compile-time default of 1K is used.

     -I interleave
		 Specify the interleave between segments.  The default is zero.

     -i 	 The size of an inode block, in bytes.	The default is to use the same size as a fragment, or in a v1 filesystem, the same size as
		 a data block.

     -L 	 Create a log-structured file system (LFS).  This is the default, and this option is provided for compatibility only.

     -M nsegs	 Specify lfs_minfreeseg, the number of segments left out of the amount allocated to user data.	A higher number increases cleaner
		 performance, while a lower number gives more usable space.  The default is based on the size of the filesystem, either 5% of the
		 total number of segments or 20 segments, whichever is larger.

     -m free space %
		 The percentage of space reserved from normal users; the minimum free space threshold.	The default value used is 10%.

     -N 	 Do not actually create the filesystem.

     -O offset	 Start the first segment this many sectors from the beginning of the partition.  The default is zero.

     -R nsegs	 Specify lfs_resvseg, the number of segments set aside for the exclusive use of the cleaner.  A larger figure reduces the likeli-
		 hood of running out of clean segments, but if lfs_resvseg is too close to lfs_minfreeseg, the cleaner will run without ceasing
		 when the filesystem becomes close to full.  The default is the larger of 15 or the quantity lfs_minfreeseg / 2 + 1 .

     -r ident	 For a v2 filesystem, specify the roll-forward identifier for the filesystem.  This identifier, a 32-bit numeric quantity, should
		 be different from that of any LFS that may previously have existed on the same disk.  By default the identifier is chosen at ran-
		 dom.

     -s size	 The size of the file system in sectors.

     -v version  Make a filesystem with the specified disk layout version.  Valid options are 1 or 2 (the default).  Note, however, that LFS ver-
		 sion 1 is deprecated.

SEE ALSO

     disktab(5), disklabel(8), diskpart(8), dumplfs(8)

     M. Seltzer, K. Bostic, M. McKusick, and C. Staelin, "An Implementation of a Log-Structured File System for UNIX", Proceedings of the Winter
     1993 USENIX Conference, pp. 315-331, January 25-29, 1993.

     J. Matthews, D. Roselli, A. Costello, R. Wang, and T. Anderson, "Improving the Performance of Log-Structured File Systems with Adaptive
     Methods", Proceedings of the Sixteenth ACM SOSP, October 1997.

HISTORY

     A newlfs command appeared in 4.4BSD, and was renamed to newfs_lfs for NetBSD 1.4.

BSD
								   July 12, 2001							       BSD