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

newfs_lfsconstruct 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.

Attempt to compute the appropriate segment size using the formula . The disk is tested for twenty seconds to discover its bandwidth and seek time.
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.
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.
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.
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.
interleave
Specify the interleave between segments. The default is zero.
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.
Create a log-structured file system (LFS). This is the default, and this option is provided for compatibility only.
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.
free space %
The percentage of space reserved from normal users; the minimum free space threshold. The default value used is 10%.
Do not actually create the filesystem.
offset
Start the first segment this many sectors from the beginning of the partition. The default is zero.
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 .
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.
size
The size of the file system in sectors.
version
Make a filesystem with the specified disk layout version. Valid options are 1 or 2 (the default). , however, that LFS version 1 is deprecated, and 64-bit volumes may not be version 1.
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.

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 1.4.

October 13, 2015 NetBSD-9.2