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NEWFS_LFS(8) NetBSD System Manager's Manual NEWFS_LFS(8)
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newfs_lfs -- construct a new LFS file system
newfs_lfs [newfs_lfs-options] special
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.
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 seg-
ment size of 1M is used.
The block size of the file system in bytes. If not speci-
fied, the block size is taken from the partition label, or if
the partition label indicates 0, a compile-time default of 8K
-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.
The fragment size of the file system in bytes. If not speci-
fied, the fragment size is taken from the partition label, or
if the partition label indicates 0, a compile-time default of
1K is used.
Specify the interleave between segments. The default is
-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 mini-
mum 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
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 vol-
umes less than 1 TB, and 64-bit for larger volumes.
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.
A newlfs command appeared in 4.4BSD, and was renamed to newfs_lfs for
NetBSD 9.0 October 13, 2015 NetBSD 9.0