NAME¶
newfs —
construct a new UFS1/UFS2 file
system
SYNOPSIS¶
newfs |
[-EJNUln]
[-L
volname]
[-O
filesystem-type]
[-S
sector-size]
[-T
disktype]
[-a
maxcontig]
[-b
block-size]
[-c
blocks-per-cylinder-group]
[-d
max-extent-size]
[-e
maxbpg]
[-f
frag-size]
[-g
avgfilesize]
[-h
avgfpdir]
[-i bytes]
[-m
free-space]
[-o
optimization]
[-p
partition]
[-r
reserved]
[-s size]
special |
DESCRIPTION¶
The
newfs utility is used to initialize and clear file systems
before first use. The
newfs utility builds a file system on
the specified special file. (We often refer to the “special file”
as the “disk”, although the special file need not be a physical
disk. In fact, it need not even be special.) 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:
- -E
- Erase the content of the disk before making the filesystem.
The reserved area in front of the superblock (for bootcode) will not be
erased.
This is a relevant option for flash based storage devices that use wear
levelling algorithms.
NB: Erasing may take as long time as writing every sector on the disk.
- -J
- Enable journaling on the new file system via gjournal. See
gjournal(8) for details.
- -L
volname
- Add a volume label to the new file system.
- -N
- Cause the file system parameters to be printed out without
really creating the file system.
- -O
filesystem-type
- Use 1 to specify that a UFS1 format file system be built;
use 2 to specify that a UFS2 format file system be built. The default
format is UFS2.
- -T
disktype
- For backward compatibility.
- -U
- Enable soft updates on the new file system.
- -a
maxcontig
- Specify the maximum number of contiguous blocks that will
be laid out before forcing a rotational delay. The default value is 16.
See tunefs(8) for more details on how to set this
option.
- -b
block-size
- The block size of the file system, in bytes. It must be a
power of 2. The default size is 16384 bytes, and the smallest allowable
size is 4096 bytes. The optimal block:fragment ratio is 8:1. Other ratios
are possible, but are not recommended, and may produce poor results.
- -c
blocks-per-cylinder-group
- The number of blocks per cylinder group in a file system.
The default is to compute the maximum allowed by the other parameters.
This value is dependent on a number of other parameters, in particular the
block size and the number of bytes per inode.
- -d
max-extent-size
- The file system may choose to store large files using
extents. This parameter specifies the largest extent size that may be
used. It is presently limited to its default value which is 16 times the
file system blocksize.
- -e
maxbpg
- Indicate 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. It must be a
power of two ranging in value between blocksize/8
and blocksize. The default is 2048 bytes.
- -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
bytes
- Specify the density of inodes in the file system. The
default is to create an inode for every (4 *
frag-size) 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. One inode is required for each distinct file, so
this value effectively specifies the average file size on the file
system.
- -l
- Enable multilabel MAC on the new file system.
- -m
free-space
- The percentage of space reserved from normal users; the
minimum free space threshold. The default value used is defined by
MINFREE
from
<ufs/ffs/fs.h>, currently 8%.
See tunefs(8) for more details on how to set this
option.
- -n
- Do not create a .snap directory on the
new file system. The resulting file system will not support snapshot
generation, so dump(8) in live mode and background
fsck(8) will not function properly. The traditional
fsck(8) and offline dump(8) will work
on the file system. This option is intended primarily for memory or
vnode-backed file systems that do not require dump(8) or
fsck(8) support.
- -o
optimization
- (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 8%, the default is
to optimize for space; if the value of minfree is
greater than or equal to 8%, the default is to optimize for
time. See tunefs(8) for more details
on how to set this option.
- -p
partition
- The partition name (a..h) you want to use in case the
underlying image is a file, so you don't have access to individual
partitions through the filesystem. Can also be used with a device, e.g.
newfs -p f
/dev/da1s3 is equivalent to newfs
/dev/da1s3f.
- -r
reserved
- The size, in sectors, of reserved space at the end of the
partition specified in special. This space will not
be occupied by the file system; it can be used by other consumers such as
geom(4). Defaults to 0.
- -s
size
- The size of the file system in sectors. This value defaults
to the size of the raw partition specified in
special less the reserved
space at its end (see -r). A size
of 0 can also be used to choose the default value. A valid
size value cannot be larger than the default one,
which means that the file system cannot extend into the reserved
space.
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(8) 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).
EXAMPLES¶
newfs /dev/ad3s1a
Creates a new ufs file system on
ad3s1a. The
newfs utility will use a block size of 16384 bytes, a
fragment size of 2048 bytes and the largest possible number of blocks per
cylinders group. These values tend to produce better performance for most
applications than the historical defaults (8192 byte block size and 1024 byte
fragment size). This large fragment size may lead to much wasted space on file
systems that contain many small files.
SEE ALSO¶
fdformat(1),
geom(4),
disktab(5),
fs(5),
bsdlabel(8),
camcontrol(8),
dump(8),
dumpfs(8),
fsck(8),
gjournal(8),
mount(8),
tunefs(8),
gvinum(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 utility appeared in
4.2BSD.