NEWFS(8) BSD System Manager's Manual NEWFS(8)
NAME
newfs -- construct a new file system
ALERT
UFS SUPPORT IS IN THE PROCESS OF BEING DEPRECATED.
SYNOPSIS
newfs [-NO] [-S sector-size] [-T disktype] [-a maxcontig] [-b block-size] [-c cylinders] [-d rotdelay]
[-e maxbpg] [-f frag-size] [-i bytes] [-k skew] [-l interleave] [-m free space]
[-n rotational positions] [-o optimization] [-p sectors] [-r revolutions] [-s size] [-t tracks]
[-u sectors] [-v volume name] [-x sectors] special
DESCRIPTION
The newfs utility replaces the more obtuse mkfs(8) program. The newfs utility builds a file system on
the specified special device basing its defaults on the information in the disk label. Typically the
defaults are reasonable, however newfs has numerous options to allow the defaults to be selectively
overridden.
The following options define the general layout policies.
-N Causes the file system parameters to be printed out without really creating the file sys-tem. system.
tem.
-O Creates a 4.3BSD format filesystem. This options is primarily used to build root filesys-tems filesystems
tems that can be understood by older boot ROMs.
-T disktype
This specifies the disk type.
-a maxcontig
This specifies the maximum number of contiguous blocks that will be laid out before forcing
a rotational delay (see the -d option). The default value is one. See tunefs(8) for more
details on how to set this option.
-b block-size
The block size of the file system, in bytes.
-c #cylinders/group
The number of cylinders per cylinder group in a file system. The default value is 16.
-d rotdelay
This specifies the expected time (in milliseconds) to service a transfer completion inter-rupt interrupt
rupt and initiate a new transfer on the same disk. The default is 4 milliseconds. See
tunefs(8) for more details on how to set this option.
-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 cylinder group. See tunefs(8) for
more details on how to set this option.
-f frag-size
The fragment size of the file system in bytes.
-i number of bytes per inode
This specifies the density of inodes in the file system. The default is to create an inode
for each 2048 bytes of data space. If fewer inodes are desired, a larger number should be
used; to create more inodes a smaller number should be given.
-m free space %
The percentage of space reserved from normal users; the minimum free space threshold. The
default value used is 10%. See tunefs(8) for more details on how to set this option.
-n rotational positions
Determines how many rotational time slots there are in one revolution of the disk.
-o optimization preference
(``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 10%, the default is to optimize for space;
if the value of minfree is greater than or equal to 10%, 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.
The following options override the standard sizes for the disk geometry. Their default values are
taken from the disk label. Changing these defaults 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 any of these values from
their defaults will make it impossible for fsck to find the alternate superblocks if the standard
superblock is lost.
-S sector-size
The size of a sector in bytes (almost never anything but 512).
-k sector 0 skew, per track
Used to describe perturbations in the media format to compensate for a slow controller.
Track skew is the offset of sector 0 on track N relative to sector 0 on track N-1 on the
same cylinder.
-l hardware sector interleave
Used to describe perturbations in the media format to compensate for a slow controller.
Interleave is physical sector interleave on each track, specified as the denominator of the
ratio:
sectors read/sectors passed over
Thus an interleave of 1/1 implies contiguous layout, while 1/2 implies logical sector 0 is
separated by one sector from logical sector 1.
-p spare sectors per track
Spare sectors (bad sector replacements) are physical sectors that occupy space at the end
of each track. They are not counted as part of the sectors/track (-u) since they are not
available to the file system for data allocation.
-r revolutions/minute
The speed of the disk in revolutions per minute.
-t #tracks/cylinder
The number of tracks/cylinder available for data allocation by the file system.
-u sectors/track
The number of sectors per track available for data allocation by the file system. This
does not include sectors reserved at the end of each track for bad block replacement (see
the -p option.)
-v volume name
Volume name (file system name) in ASCII or UTF-8 format. The default is "untitled".
-x spare sectors per cylinder
Spare sectors (bad sector replacements) are physical sectors that occupy space at the end
of the last track in the cylinder. They are deducted from the sectors/track (-u) of the
last track of each cylinder since they are not available to the file system for data allo-cation. allocation.
cation.
SEE ALSO
fs(5), dumpfs(8), fdisk(8), fsck(8), mount(8), pdisk(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.
4.2 Berkeley Distribution May 3, 1995 4.2 Berkeley Distribution
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