NEWFS(8) NetBSD System Manager's Manual NEWFS(8)
NAME
newfs -- construct a new file system
SYNOPSIS
newfs [-FINZ] [-a maxcontig] [-B byte-order] [-b block-size] [-d maxbsize] [-e maxbpg] [-f frag-size] [-g avgfilesize] [-h avgfpdir] [-i bytes-per-inode] [-m free-space] [-n inodes] [-O filesystem-format] [-o optimization] [-S sector-size] [-s size] [-T disk-type] [-v volname] [-V verbose] special
DESCRIPTION
newfs is used to initialize and clear file systems before first use. Before running newfs the disk must be labeled using disklabel(8). newfs builds a file system on the specified special device basing its defaults on the information in the disk label. Typically the defaults are reason- able, however newfs has numerous options to allow the defaults to be selectively overridden. Options with numeric arguments may contain an optional (case-insensitive) suffix: b Bytes; causes no modification. (Default) k Kilo; multiply the argument by 1024 m Mega; multiply the argument by 1048576 g Giga; multiply the argument by 1073741824 t Tera; multiply the argument by 1099511627776 The following options define the general layout policies. -a maxcontig This sets the obsolete maxcontig parameter. -B byte-order Specify the metadata byte order of the file system to be cre- ated. Valid byte orders are `be' and `le'. If no byte order is specified, the file system is created in host byte order. -b block-size The block size of the file system, in bytes. It must be a power of two. The smallest allowable size is 4096 bytes. The default size depends upon the size of the file system: file system size block-size < 20 MB 4 KB < 1024 MB 8 KB >= 1024 MB 16 KB -d maxbsize Set the maximum extent size to maxbsize. -e maxbpg This indicates the maximum number of blocks any single file can allocate out of a cylinder group before it is forced to begin allocating blocks from another cylinder group. The default is about one quarter of the total blocks in a cylin- der group. See tunefs(8) for more details on how to set this option. -F Create a file system image in special. The file system size needs to be specified with ``-s size''. No attempts to use or update the disk label will be made. -f frag-size The fragment size of the file system in bytes. It must be a power of two ranging in value between block-size/8 and block-size. The optimal block-size:frag-size ratio is 8:1. Other ratios are possible, but are not recommended, and may produce unpredictable results. The default size depends upon the size of the file system: file system size frag-size < 20 MB 0.5 KB < 1024 MB 1 KB >= 1024 MB 2 KB -g avgfilesize The expected average file size for the file system. -h avgfpdir The expected average number of files per directory on the file system. -I Do not require that the file system type listed in the disk label is `4.2BSD' or `Apple UFS'. -i bytes-per-inode This specifies the density of inodes in the file system. If fewer inodes are desired, a larger number should be used; to create more inodes a smaller number should be given. The default is to create an inode for every (4 * frag-size) bytes of data space: file system size bytes-per-inode < 20 MB 2 KB < 1024 MB 4 KB >= 1024 MB 8 KB -m free-space The percentage of space reserved from normal users; the mini- mum free space threshold. The default value used is 5%. See tunefs(8) for more details on how to set this option. -N Causes the file system parameters to be printed out without really creating the file system. -n inodes This specifies the number of inodes for the filesystem. If both -i and -n are specified then -n takes precedence. -O filesystem-format Select the filesystem-format 0 4.3BSD; This option is primarily used to build root file systems that can be understood by older boot ROMs. 1 FFSv1; normal fast-filesystem (default). 2 FFSv2; enhanced fast-filesystem (suited for more than 1 Terabyte capacity, access control lists). To create an LFS filesystem see newfs_lfs(8). To create a Linux Ext2 filesystem see newfs_ext2fs(8). -o optimization Optimization preference; either ``space'' or ``time''. The file system can either be instructed to try to minimize the time spent allocating blocks, or to try to minimize the space fragmentation on the disk. If the value of minfree (see above) is less than 5%, the default is to optimize for space; if the value of minfree is greater than or equal to 5%, the default is to optimize for time. See tunefs(8) for more details on how to set this option. -s size The size of the file system in sectors. An `s' suffix will be interpreted as the number of sectors (the default). All other suffixes are interpreted as per other numeric argu- ments, except that the number is converted into sectors by dividing by the sector size (as specified by -S secsize) after suffix interpretation. If no -s size is specified then the filesystem size defaults to that of the partition, or, if -F is specified, the exist- ing file. If size is negative the specified size is subtracted from the default size (reserving space at the end of the partition). -T disk-type Uses information for the specified disk from /etc/disktab instead of trying to get the information from the disk label. -v volname This specifies that an Apple UFS filesystem should be created with the given volume name. -V verbose This controls the amount of information written to stdout: 0 No output 1 Overall size and cylinder group details. 2 A progress bar (dots ending at right hand margin). 3 The first few super-block backup sector numbers are displayed before the progress bar. 4 All the super-block backup sector numbers are dis- played (no progress bar). The default is 3. If -N is specifed newfs stops before out- putting the progress bar. -Z Pre-zeros the file system image created with -F. This is necessary if the image is to be used by vnd(4) (which doesn't support file systems with `holes'). The following option overrides the standard sizes for the disk geometry. The default value is taken from the disk label. Changing this default is useful only when using newfs to build a file system whose raw image will eventually be used on a different type of disk than the one on which it is initially created (for example on a write-once disk). Note that changing this value from its default will make it impossible for fsck_ffs(8) to find the alternative superblocks if the standard superblock is lost. -S sector-size The size of a sector in bytes (almost never anything but 512). Defaults to 512.
NOTES
The file system is created with `random' inode generation numbers to improve NFS security. The owner and group ids of the root node of the new file system are set to the effective uid and gid of the user initializing the file system. For the newfs command to succeed, the disk label should first be updated such that the fstype field for the partition is set to `4.2BSD' or `Apple UFS', unless -F or -I is used. To create and populate a filesystem image within a file use the makefs(8) utility. The partition size is found using fstat(2) not by inspecting the diskla- bel. The block size and fragment size will be written back to the disklabel only if the last character of special references the same par- tition as the minor device number. that provide disk like block and character devices.
SEE ALSO
fstat(2), disktab(5), fs(5), disklabel(8), diskpart(8), dumpfs(8), fsck_ffs(8), makefs(8), mount(8), mount_mfs(8), newfs_ext2fs(8), newfs_lfs(8), newfs_msdos(8), tunefs(8) M. McKusick, W. Joy, S. Leffler, and R. Fabry, "A Fast File System for UNIX,", ACM Transactions on Computer Systems 2, 3, pp 181-197, August 1984, (reprinted in the BSD System Manager's Manual).
HISTORY
The newfs command appeared in 4.2BSD. NetBSD 5.0.2 December 10, 2007 NetBSD 5.0.2
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