MirOS Manual: mfs(8), mount_mfs(8), newfs(8)

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

NAME

     newfs, mount_mfs - construct a new file system

SYNOPSIS

     newfs [-NOq] [-a maxcontig] [-b block-size] [-c cylinders] [-d rotdelay]
           [-e maxbpg] [-f frag-size] [-g avgfilesize] [-h avgfpdir]
           [-i bytes] [-k skew] [-l interleave] [-m free-space] [-n nrpos]
           [-o optimization] [-p sectors] [-r revolutions] [-S sector-size]
           [-s size] [-t fstype] [-u sectors] [-x sectors] [-z tracks] special

     mount_mfs [-a maxcontig] [-b block-size] [-c cylinders] [-d rotdelay]
           [-e maxbpg] [-f frag-size] [-i bytes] [-m free space] [-o options]
           [-P file] [-s size] special node

DESCRIPTION

     Before running newfs or mount_mfs, 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 reasonable, although 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 sys-
     tem are lost when the file system is unmounted. If mount_mfs is sent a
     signal while running, for example during system shutdown, it will attempt
     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 pri-
     mary 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. If the keyword "swap" is used instead of a special file
     name, default configuration parameters will be used. (This option is use-
     ful when trying to use mount_mfs on a machine without any disks.)

     Both newfs and mount_mfs now have the functionality of fsirand(8) built
     in, so it is not necessary to run fsirand(8) manually unless you wish to
     re-randomize the file system (or list the inode generation numbers).

     The following options define the general layout policies:

     -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 depends on the block size (4
                 for 16KB blocks, 8 for 8KB blocks, and 16 for 4KB blocks).
                 See tunefs(8) for more details on how to set this option.

     -b block-size
                 The block size of the file system, in bytes. The default is
                 16KB.

     -c cylinders
                 The number of cylinders per cylinder group in a file system.
                 The default is to use as many as fit with the other parame-
                 ters given.

     -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
                 2048.

     -g avgfilesize
                 The expected average file size for the file system in bytes.

     -h avgfpdir
                 The expected average number of files per directory on the
                 file system.

     -i bytes    This specifies the density of inodes in the file system. The
                 default is to create an inode for each 8192 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 5%.
                 See tunefs(8) for more details on how to set this option.

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

     -n nrpos    The number of distinct rotational positions. The default is
                 1.

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

     -o optimization
                 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. Unless an
                 optimization has been specified, 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.

     -q          Operate in quiet mode. With this option, newfs will not print
                 extraneous information like superblock backups.

     -s size     The size of the file system in sectors. The maximum size of a
                 file system is 2,147,483,647 (2^31 - 1) sectors, which is
                 slightly less than 1TB.

     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(8) to find the alternate superblocks if the standard su-
     perblock is lost.

     -k skew     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 interleave
                 Used to describe perturbations in the media format to compen-
                 sate for a slow controller. Interleave is physical sector in-
                 terleave 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 sectors  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
                 The speed of the disk in revolutions per minute.

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

     -t fstype   Set the file system type of which file system you wish to
                 create. newfs will be smart enough to run the alternate
                 newfs_XXX program instead.

     -u sectors  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 sectors  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.

     -z tracks   The number of tracks/cylinder available for data allocation
                 by the file system.

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

     These options are as follows:

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

     -P file
             If file is a directory, populate the created mfs file system with
             the contents of the directory. If file is a block device, popu-
             late the created mfs file system with the contents of the FFS
             file system contained on the device.

     If the -P file option is not used, the owner and mode of the created mfs
     file system will be the same as the owner and mode of the mount point.

ENVIRONMENT

     TMPDIR  Directory in which to create temporary mount points for use by
             mount_mfs -P instead of /tmp.

SEE ALSO

     disktab(5), fs(5), disklabel(8), dumpfs(8), fsck(8), fsirand(8),
     growfs(8), mount(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.

MirOS BSD #10-current           March 27, 1994                               3

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