NAME
newfs - construct a new UFS1/UFS2 file system
SYNOPSIS
newfs [-JNUln] [-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 systems 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 reasonable, however
newfs has numerous options to allow the defaults to be selectively
overridden.
The following options define the general layout policies:
-J Enable journaling on the new file system via gjournal.
-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 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.
-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. 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), disktab(5), fs(5), bsdlabel(8), camcontrol(8), dump(8),
dumpfs(8), fsck(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.