mkfs(1M_UFS) (UFS) mkfs(1M_UFS)
NAME
mkfs (ufs) - construct a ufs file system
SYNOPSIS
mkfs [-F ufs] [generic_options] special
mkfs [-F ufs] [generic_options] [-o specific_options] special size
DESCRIPTION
generic_options are options supported by the generic mkfs
command.
mkfs constructs a file system by writing on the special file
special unless the `-o N' flag has been specified. The
numeric size specifies the number of logical 512 byte sectors
in the file system. mkfs builds a file system with a root
directory and a lost+found directory [see fsck(1M)].
The options are:
-F ufs
Specifies the ufs-FSType.
-o Specify ufs file system-specific options. These options
can be specified in any order, but must be separated by
commas. The following options are available:
N Do not write the file system to the special
file. This suboption gives all the information
needed to create a file system but does not
create it.
nsect=n The number of sectors per track on the disk.
The default is 18.
ntrack=n
The number of tracks per cylinder on the disk.
The default is 9.
bsize=n The primary block size for files on the file
system. It must be a power of two, currently
selected from 4096 (the default) or 8192.
fragsize=n
The fragment size for files on the file system.
The fragsize represents the smallest amount of
disk space that will be allocated to a file. It
Copyright 1994 Novell, Inc. Page 1
mkfs(1M_UFS) (UFS) mkfs(1M_UFS)
must be a power of two currently selected from
the range 512 to 8192. The default is 1024.
cgsize=n
The number of disk cylinders per cylinder group.
n must be in the range 1 to 32. cgsize has
different defaults, depending on the size of the
cylinder group. If the cylinder group is less
than 3/4 MB, cgsize defaults to 16. If the
cylinder group is between 3/4 and 1.5 MB, cgsize
defaults to 12. If the cylinder group is
greater than 1.5 MB, cgsize defaults to 8.
nbpi=n The number of bytes for which one inode block is
allocated. The default currently set at one
inode block for every 2048 bytes.
free=n The minimum percentage of free disk space
allowed. Once the file system capacity reaches
this threshold, only a privileged user is
allowed to allocate disk blocks. The default
value is 10%. It is inadvisable to reduce the
allocation of free space below the default level
because this may adversely affect performance.
free also determines when a filesystem will
automatically switch between time optimization
and space optimization.
rps=n The rotational speed of the disk, in revolutions
per second. The default is 60.
opt=s|t Space or time optimization preference; s
specifies optimization for space, t specifies
optimization for time. The default is t.
apc=n The number of alternates per cylinder (SCSI
devices only). The default is 0.
gap=n The expected time (in milliseconds) to service a
transfer completion interrupt and initiate a new
transfer on the same disk. It is used to decide
how much rotational spacing to place between
successive blocks in a file. The default is 4.
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mkfs(1M_UFS) (UFS) mkfs(1M_UFS)
C Some applications that pre-date SVR4 do not work
on file systems with more than 64K inodes.
Therefore, when the number of inodes for the
file system being built exceeds the 64K limit,
mkfs prompts the user to confirm that he or she
indeed wants the large number of inodes. The -o
C option silences this mkfs prompt and limits
the number of inodes to a maximum of 64K,
ensuring perfect binary compatibility with the
pre-Release 4 UNIX System.
L When the number of inodes for the file system
being built exceeds the 64K limit, mkfs prompts
the user to confirm that he or she indeed wants
the large number of inodes. The -o L option
silences this prompt and allows the user to
create a file system with more than 64K inodes.
special
mkfs constructs a file system by writing on the special
file.
size Specify the number of logical 512 byte sectors in the
file system. The largest file system size is a maximum of
4,194,304 512-byte sectors (2 gigabytes).
NOTICES
The number of inodes is calculated as a function of the file
system size, but can be modified with the nbpi option. For
those who want a file system suitable for lots of tiny files
(smaller than one block), the nbpi parameter may be used to
increase the number of inodes.
You should keep a note of spare superblock copies in the ufs
file system, so that in the event of superblock corruption,
you will know which blocks contain spare entries.
REFERENCES
dir(4UFS), fsck(1M), generic mkfs(1M), ufs-specific fs(4UFS)
Copyright 1994 Novell, Inc. Page 3