newfs_lfs(8) - NetBSD Manual Pages

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NEWFS_LFS(8)            NetBSD 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 seg- ment size of 1M is used. -b block-size 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 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 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. -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 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 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 vol- umes 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 9.99 October 13, 2015 NetBSD 9.99
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