newfs(8)

NAME

newfs - construct a new UFS1/UFS2 file system

SYNOPSIS

newfs  [-NUln]  [-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] [-s size] special

DESCRIPTION

The newfs utility is used to initialize and clear file sys

tems before
first use. Before running newfs the disk must be labeled

using
bsdlabel(8). 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 reason

able, however
newfs has numerous options to allow the defaults to be se

lectively overridden.

The following options define the general layout policies:

-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 recom

mended, 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 us

ing 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 de

fault is about
one quarter of the total blocks in a cylinder group.

See
tunefs(8) for more details on how to set this op

tion.

-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 de

fined by
MINFREE from 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 sys

tem. The

resulting file system will not support snapshot gen

eration, 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 primar

ily 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 in

structed 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.

-s size

The size of the file system in sectors. This value

defaults to
the size of the raw partition specified in special

(in other
words, newfs will use the entire partition for the

file system).

The following options override the standard sizes for the

disk geometry.
Their default values are taken from the disk label. Chang

ing 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 his

torical
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), disktab(5), fs(5), bsdlabel(8), camcontrol(8),

dump(8),
dumpfs(8), fsck(8), mount(8), tunefs(8), vinum(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.

BSD January 21, 2005

BSD