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NEWFS(8)			   BSD System Manager's Manual				 NEWFS(8)

NAME
     newfs -- construct a new file system

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] [-x sectors] special

DESCRIPTION
     Newfs replaces the more obtuse mkfs(8) program.  Before running newfs the disk must be
     labeled using disklabel(8).  Newfs builds a file system on the specified special device bas-
     ing its defaults on the information in the disk label.  Typically the defaults are reason-
     able, 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 primarily used to build
		 root filesystems that can be understood by older boot ROMs.

     -T 	 Uses information for the specified disk from /etc/disktab instead of trying to
		 get the information from a disklabel.

     -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 comple-
		 tion 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
		 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.

     -i number of bytes per inode
		 This specifies the density of inodes in the file system.  The default is to cre-
		 ate 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 minimum 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 mini-
		 mize the time spent allocating blocks, or to try to minimize the space fragmen-
		 tation 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 val-
     ues 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 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 compensate for a slow con-
		 troller.  Track skew is the offset of sector 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 compensate for a slow con-
		 troller.  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 sys-
		 tem.  This does not include sectors reserved at the end of each track for bad
		 block replacement (see the -p option.)

     -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 cylinder.	They are deducted from the sec-
		 tors/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
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