.\"	$NetBSD: newfs_lfs.8,v 1.13 2001/07/13 20:30:20 perseant Exp $
.\"
.\" Copyright (c) 1993
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.\"    without specific prior written permission.
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.\"     @(#)newlfs.8	8.1 (Berkeley) 6/19/93
.\"
.Dd July 12, 2001
.Dt NEWFS_LFS 8
.Os
.Sh NAME
.Nm newfs_lfs
.Nd construct a new LFS file system
.Sh SYNOPSIS
.Nm
.Op Ar newfs_lfs-options
.Ar special
.Sh DESCRIPTION
.Nm
builds a log-structured file system on the specified special
device basing its defaults on the information in the disk label.
Before running 
.Nm
the disk must be labeled using 
.Xr disklabel 8 ,
the proper fstype is 4.4LFS.  Reasonable values for the
.Li fsize, 
.Li bsize,
and
.Li sgs
fields are 1024, 8192, and 7 respectively.
.Pp
The following options define the general layout policies.
.Bl -tag -width Fl
.It Fl A
Attempt to compute the appropriate segment size using the formula
\fB4 * bandwidth * access time\fR.  The disk is tested for twenty seconds
to discover its bandwidth and seek time. 
.It Fl B Ar 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 partition 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.
.It Fl b Ar 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 partition label
indicates 0, a compile-time default of 8K is used.
.It Fl F
Force creation of an LFS even on a partition labeled as another type.
.Nm
will use compile-time default values for block and fragment size, and segment
shift, unless these are overridden by command-line flags.
.It Fl f Ar 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.
.It Fl I Ar interleave
Specify the interleave between segments.  The default is zero.
.It Fl 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.
.It Fl L
Create a log-structured file system (LFS).  This is the default, and this
option is provided for compatibility only.
.It Fl M Ar nsegs
Reserve this many segments for use exclusively by the cleaner, instead
of letting
.Nm
do the computation.  Do not use this option.
.It Fl m Ar free space \&%
The percentage of space reserved from normal users; the minimum
free space threshold.  The default value used is 10%.
.It Fl N
Do not actually create the filesystem.
.It Fl O Ar offset
Start the first segment this many sectors from the beginning of the
partition.  The default is zero.
.It Fl r Ar 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 random.
.It Fl s Ar size
The size of the file system in sectors.
.It Fl v Ar version
Make a filesystem with the specified disk layout version.  Valid options
are 1 (the default) or 2.
.El
.Sh SEE ALSO
.Xr disktab 5 ,
.\" .Xr fs 5 ,
.Xr dumplfs 8 ,
.Xr disklabel 8 ,
.Xr diskpart 8
.\" .Xr tunefs 8
.Rs
.%A M. Seltzer
.%A K. Bostic
.%A M. McKusick
.%A C. Staelin
.%T "An Implementation of a Log-Structured File System for UNIX"
.%J "Proceedings of the Winter 1993 USENIX Conference"
.%D January 25-29, 1993
.%P pp. 315-331
.Re
.Rs
.%A J. Matthews
.%A D. Roselli
.%A A. Costello
.%A R. Wang
.%A T. Anderson
.%T "Improving the Performance of Log-Structured File Systems with Adaptive Methods"
.%J "Proceedings of the Sixteenth ACM SOSP"
.%D October 1997
.Re
.Sh HISTORY
A \fBnewlfs\fR
command appeared in
.Bx 4.4 ,
and was renamed to 
.Nm
for
.Nx 1.4.