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 system.
-O Creates a 4.3BSD format filesystem. This options is primar-
ily used to build root filesystems 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 interrupt 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 cylin-
der 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 mini-
mum 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 impos-
sible 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 compen-
sate for a slow controller. Track skew is the offset of sec-
tor 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 compen-
sate 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 cylin-
der. 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 allocation.
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
Mac OS X 10.5 - Generated Sun Oct 28 21:47:12 EDT 2007