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 sys-
     tem on the specified special device basing its defaults on the information in the disk label.  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.

     -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 completion 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 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.

     -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 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 opti-
		 mize 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 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 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 controller.  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 controller.  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 system.  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 sectors/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