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

NAME
     newfs - construct a new file system

SYNOPSIS
     newfs [-B byte-order] [-FINOZ] [-S sector-size] [-T disk-type] [-a
           maxcontig] [-b block-size] [-c cpg] [-d rotdelay] [-e maxbpg] [-f
           frag-size] [-g avgfilesize] [-h avgfpdir] [-i bytes-per-inode] [-k
           skew] [-l interleave] [-m free-space] [-n rotational-positions] [-o
           optimization] [-p track-spares] [-r revolutions] [-s size] [-t
           ntracks] [-u nsectors] [-x sectors] special

DESCRIPTION
     newfs is used to initialize and clear file systems before first use.  Be-
     fore running newfs the disk must be labeled using disklabel(8).  newfs
     builds a file system on the specified special device basing 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 se-
     lectively overridden.

     Options with numeric arguments may contain an optional (case-insensitive)
     suffix:
           b    Bytes; causes no modification. (Default)
           k    Kilo; multiply the argument by 1024
           m    Mega; multiply the argument by 1048576
           g    Giga; multiply the argument by 1073741824

     The following options define the general layout policies.

     -B byte-order
                 Specify the metadata byte order of the file system to be cre-
                 ated.  Valid byte orders are `be' and `le'.  If no byte order
                 is specified, the file system is created in host byte order.

     -F          Create a file system image in special.  The file system size
                 needs to be specified with ``-s size''.  No attempts to use
                 or update the disk label will be made.

     -I          Do not require that the file system type listed in the disk
                 label is `4.2BSD'.

     -N          Causes the file system parameters to be printed out without
                 really creating the file system.

     -O          Creates a 4.3BSD format file system.  This option is primari-
                 ly used to build root file systems that can be understood by
                 older boot ROMs.

     -T disk-type
                 Uses information for the specified disk from /etc/disktab in-
                 stead of trying to get the information from the disk label.

     -Z          Pre-zeros the file system image created with -F. This is nec-
                 essary if the image is to be used by vnd(4) (which doesn't
                 support file systems with `holes').

     -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 8.  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 two.  The smallest allowable size is 4096 bytes.
                 The default size depends upon the size of the file system:

                       file system size  block-size
                       < 20 MB           4 KB
                       < 1024 MB         8 KB
                       >= 1024 MB        16 KB

     -c cpg      The number of cylinders 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 pa-
                 rameters, in particular the block size and the number of
                 bytes per inode.

     -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.  It must be a
                 power of two ranging in value between block-size/8 and block-
                 size.  The optimal block-size:frag-size ratio is 8:1.  Other
                 ratios are possible, but are not recommended, and may produce
                 unpredictable results.  The default size depends upon the
                 size of the file system:

                       file system size  frag-size
                       < 20 MB           0.5 KB
                       < 1024 MB         1 KB
                       >= 1024 MB        2 KB

     -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-per-inode
                 This specifies the density of inodes in the file system.  If
                 fewer inodes are desired, a larger number should be used; to
                 create more inodes a smaller number should be given.  The de-
                 fault is to create an inode for every (4 * frag-size) bytes
                 of data space:

                       file system size  bytes-per-inode
                       < 20 MB           2 KB
                       < 1024 MB         4 KB
                       >= 1024 MB        8 KB

     -m free-space
                 The percentage of space reserved from normal users; the mini-
                 mum free space threshold.  The default value used is 5%.  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
                 Optimization preference; either ``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 5%, the default is to optimize for space;
                 if the value of minfree is greater than or equal to 5%, the
                 default is to optimize for time.  See tunefs(8) for more de-
                 tails on how to set this option.

     -s size     The size of the file system in sectors.  An `s' suffix will
                 be interpreted as the number of sectors (the default).  All
                 other suffixes are interpreted as per other numeric argu-
                 ments, except that the number is converted into sectors by
                 dividing by the sector size (as specified by -S secsize) af-
                 ter suffix interpretation.

     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_ffs(8) to find the alternative superblocks if the standard
     superblock is lost.

     -S sector-size
                 The size of a sector in bytes (almost never anything but
                 512).  Defaults to 512.

     -k skew     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 interleave
                 Hardware sector interleave.  Used to describe perturbations
                 in the media format to compensate for a slow controller.  In-
                 terleave is physical sector interleave on each track, speci-
                 fied 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 track-spares
                 Spare sectors per track.  Spare sectors (bad sector replace-
                 ments) are physical sectors that occupy space at the end of
                 each track.  They are not counted as part of the sectors per
                 track (-u) since they are not available to the file system
                 for data allocation.

     -r revolutions
                 The speed of the disk in revolutions per minute.

     -t ntracks  The number of tracks per cylinder available for data alloca-
                 tion by the file system.

     -u nsectors
                 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 cylin-
                 der.  They are deducted from the sectors per track (-u) of
                 the last track of each cylinder since they are not available
                 to the file system for data allocation.

NOTES
     If the file system will be exported over NFS, the fsirand(8) utility
     should be run after newfs to improve security.

     The owner and group ids of the root node of the new file system are set
     to the effective uid and gid of the user initializing the file system.

     For the newfs command to succeed, the disk label should first be updated
     such that the fstype field for the partition is set to `4.2BSD', unless
     -F or -I is used.

SEE ALSO
     disktab(5), fs(5), disklabel(8), diskpart(8), dumpfs(8), fsck_ffs(8),
     fsirand(8), mount(8), mount_mfs(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.

NetBSD 1.6                     February 20, 2002                             4

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