newfs.8   [plain text]


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.\"     @(#)newfs.8	8.6 (Berkeley) 5/3/95
.\"
.Dd May 3, 1995
.Dt NEWFS 8
.Os BSD 4.2
.Sh NAME
.Nm newfs 
.Nd construct a new file system
.Sh ALERT
UFS SUPPORT IS IN THE PROCESS OF BEING DEPRECATED.
.Sh SYNOPSIS
.Nm
.Op Fl NO
.Op Fl S Ar sector-size
.Op Fl T Ar disktype
.Op Fl a Ar maxcontig
.Op Fl b Ar block-size
.Op Fl c Ar cylinders
.Op Fl d Ar rotdelay
.Op Fl e Ar maxbpg
.Op Fl f Ar frag-size
.Op Fl i Ar bytes
.Op Fl k Ar skew
.Op Fl l Ar interleave
.Op Fl m Ar free space
.Op Fl n Ar rotational positions
.Op Fl o Ar optimization
.Op Fl p Ar sectors
.Op Fl r Ar revolutions
.Op Fl s Ar size
.Op Fl t Ar tracks
.Op Fl u Ar sectors
.Op Fl v Ar volume name
.Op Fl x Ar sectors
.Ar special
.Sh DESCRIPTION
The
.Nm
utility replaces the more obtuse
.Xr mkfs 8
program.
The
.Nm
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
.Nm
has numerous options to allow the defaults to be selectively overridden.
.Pp
The following options define the general layout policies.
.Bl -tag -width Fl
.It Fl N
Causes the file system parameters to be printed out
without really creating the file system.
.It Fl O
Creates a 4.3BSD format filesystem.
This options is primarily used to build root filesystems
that can be understood by older boot ROMs.
.It Fl T Ar disktype
This specifies the disk type.
.It Fl a Ar maxcontig
This specifies the maximum number of contiguous blocks that will be
laid out before forcing a rotational delay (see the
.Fl d
option).
The default value is one.
See
.Xr tunefs 8
for more details on how to set this option.
.It Fl b Ar block-size
The block size of the file system, in bytes.  
.It Fl c Ar #cylinders/group
The number of cylinders per cylinder group in a file system.
The default value is 16.
.It Fl d Ar 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
.Xr tunefs 8
for more details on how to set this option.
.ne 1i
.It Fl e Ar 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
.Xr tunefs 8
for more details on how to set this option.
.It Fl f Ar frag-size
The fragment size of the file system in bytes.
.It Fl i Ar 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.
.It Fl m Ar free space \&%
The percentage of space reserved from normal users; the minimum free
space threshold.
The default value used is 10%.
See
.Xr tunefs 8
for more details on how to set this option.
.It Fl n Ar rotational\ positions
Determines how many rotational time slots there are in
one revolution of the disk.
.It Fl o Ar optimization\ preference
.Pq ``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
.Xr tunefs 8
for more details on how to set this option.
.It Fl s Ar size
The size of the file system in sectors.
.El
.Pp
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
.Nm 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 
.Xr fsck
to find the alternate superblocks if the standard superblock is lost.
.Bl -tag -width Fl
.It Fl S Ar sector-size
The size of a sector in bytes (almost never anything but 512).
.It Fl k Ar 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.
.It Fl l Ar 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:
.Dl 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.
.It Fl p Ar 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
.Pq Fl u
since they are not available to the file system for data allocation.
.It Fl r Ar revolutions/minute
The speed of the disk in revolutions per minute.
.ne 1i
.It Fl t Ar #tracks/cylinder
The number of tracks/cylinder available for data allocation by the file
system.
.It Fl u Ar 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
.Fl p
option.)
.It Fl v Ar volume name
Volume name (file system name) in ASCII or UTF-8 format.
The default is
.Qo untitled Qc .
.It Fl x Ar 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
.Pq Fl u
of the last track of each cylinder since they are not available to the file
system for data allocation.
.El
.Pp
.Sh SEE ALSO
.Xr fs 5 ,
.Xr dumpfs 8 ,
.Xr fdisk 8 ,
.Xr fsck 8 ,
.Xr mount 8 ,
.Xr pdisk 8 ,
.Xr tunefs 8
.Rs
.%A M. McKusick
.%A W. Joy
.%A S. Leffler
.%A R. Fabry
.%T A Fast File System for UNIX ,
.%J ACM Transactions on Computer Systems 2
.%V 3
.%P pp 181-197
.%D August 1984
.%O (reprinted in the BSD System Manager's Manual)
.Re
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.2 .