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@(#)newlfs.8 8.1 (Berkeley) 6/19/93
.Dd October 13, 2015 .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.
p
The following options define the general layout policies.
l -tag -width Fl t Fl A Attempt to compute the appropriate segment size using the formula
.Em 4 * bandwidth * access time .
The disk is tested for twenty seconds
to discover its bandwidth and seek time.
t 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.
t 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.
t 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.
t 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.
t Fl I Ar interleave Specify the interleave between segments.
The default is zero.
t 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.
t Fl L Create a log-structured file system (LFS).
This is the default, and this
option is provided for compatibility only.
t Fl M Ar nsegs Specify
.Em 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.
t Fl m Ar free space % The percentage of space reserved from normal users; the minimum
free space threshold.
The default value used is 10%.
t Fl N Do not actually create the filesystem.
t Fl O Ar offset Start the first segment this many sectors from the beginning of the
partition.
The default is zero.
t Fl R Ar nsegs Specify
.Em lfs_resvseg ,
the number of segments set aside for the exclusive use of the cleaner.
A larger figure reduces the likelihood of running out of clean segments,
but if
.Em lfs_resvseg
is too close to
.Em 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
.Em lfs_minfreeseg
/ 2 + 1 .
t 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.
t Fl s Ar size The size of the file system in sectors.
t Fl v Ar version Make a filesystem with the specified disk layout version.
Valid options are 1 or 2 (the default).
.Em Note ,
however, that LFS version 1 is deprecated, and 64-bit volumes may not
be version 1.
t Fl w Ar bitwidth Create a filesystem using the specified bit width: 32 or 64.
32-bit LFS volumes are limited to 2TB in size; 64-bit LFS volumes are
not, but incur additional overhead from having larger metadata
structures.
The default is 32-bit for volumes less than 1 TB, and 64-bit for
larger volumes.
.El
.Sh SEE ALSO
.Xr disktab 5 ,
.Xr fs 5 ,
.Xr disklabel 8 ,
.Xr diskpart 8 ,
.Xr dumplfs 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
c newlfs command appeared in
x 4.4 , and was renamed to
.Nm
for
.Nx 1.4 .
Indexes created Thu Sep 25 02:09:54 GMT 2025