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.

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.