Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
NEWFS(8)		  BSD System Manager's Manual		      NEWFS(8)

NAME
     newfs, mount_mfs -- construct a new file system

SYNOPSIS
     newfs [-NO] [-S sector-size] [-a maxcontig] [-b block-size]
	   [-c cylinders] [-d rotdelay]	[-e maxbpg] [-f	frag-size] [-i bytes]
	   [-k skew] [-l interleave] [-m free space] [-o optimization]
	   [-p sectors]	[-r revolutions] [-s size] [-t tracks] [-u sectors]
	   [-x sectors]	special
     mount_mfs [-N] [-F	file] [-T disktype] [-a	maxcontig] [-b block-size]
	   [-c cylinders] [-d rotdelay]	[-e maxbpg] [-f	frag-size] [-i bytes]
	   [-m free space] [-o options]	[-s size] special node

DESCRIPTION
     Newfs replaces the	more obtuse mkfs(8) program.  Before running newfs or
     mount_mfs,	the disk must be labeled using disklabel(8).  Newfs builds a
     file system on the	specified special device.  Typically the defaults are
     reasonable, however newfs has numerous options to allow the defaults to
     be	selectively overridden.

     Mount_mfs is used to build	a file system in virtual memory	and then mount
     it	on a specified node.  Mount_mfs	exits and the contents of the file
     system are	lost when the file system is unmounted.	 If mount_mfs is sent
     a signal while running, for example during	system shutdown, it will at-
     tempt to unmount its corresponding	file system.  The parameters to
     mount_mfs are the same as those to	newfs.	The special file is only used
     to	read the disk label which provides a set of configuration parameters
     for the memory based file system.	The special file is typically that of
     the primary swap area, since that is where	the file system	will be	backed
     up	when free memory gets low and the memory supporting the	file system
     has to be paged.

     The following options define the general layout policies.

     -T	disktype
		 For backward compatibility and	for mount_mfs.

     -F	file	 mount_mfs will	use this file for the image of the filesystem.
		 When mount_mfs	exits, this file will be left behind.

     -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 primar-
		 ily used to build root	filesystems that can be	understood by
		 older boot ROMs.

     -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 0 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 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.	 The default
		 is 1024 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 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.

     -m	free space %
		 The percentage	of space reserved from normal users; the mini-
		 mum free space	threshold.  The	default	value used is defined
		 by MINFREE from <ufs/ffs/fs.h>, currently 8%.	See tunefs(8)
		 for more details on how to set	this option.

     -n	number of distinguished	rotational positions
		 Determines how	many rotational	time slots there are in	one
		 revolution of the disk.  Defaults to 1, which essentially
		 disables the rotational position table.

     -o	optimization preference
		 (``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 de-
		 fault 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 op-
		 tion.

     -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 de-
     faults 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	impos-
     sible for fsck to find the	alternate superblocks if the standard su-
     perblock 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 compen-
		 sate for a slow controller.  Track skew is the	offset of sec-
		 tor 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 compen-
		 sate 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.  The default is 1.	 If zero is specified,
		 the value from	the disklabel will be used.

     -u	sectors/track
		 The number of sectors per track available for data allocation
		 by the	file system.  The default is 4096.  If zero is speci-
		 fied, the value from the disklabel will be used.  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 cylin-
		 der.  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.

     The options to the	mount_mfs command are as described for the newfs com-
     mand, except for the -o option.

     That option is as follows:

     -o	     Options are specified with	a -o flag followed by a	comma sepa-
	     rated string of options.  See the mount(8)	man page for possible
	     options and their meanings.

EXAMPLES
	   mount_mfs -s=20480 -o nosuid,nodev /dev/sd0b	/tmp

     Mount a 10240 KB large memory file	system on /tmp,	with mount(8) options
     nosuid and	nodev.

SEE ALSO
     fdformat(1), disktab(5), fs(5), disklabel(8), diskpart(8),	dumpfs(8),
     fsck(8), mount(8),	scsiformat(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	March 27, 1994	     4.2 Berkeley Distribution

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | HISTORY

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=newfs&manpath=FreeBSD+2.2.5-RELEASE>

home | help