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NEWFS_LFS(8) 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
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.
-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 partition 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
likelihood 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 random.
-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 version 1 is deprecated, and 64-bit volumes may not be
version 1.
-w 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.
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.
NetBSD 10.99 October 13, 2015 NetBSD 10.99