mkfs_ufs(1M)
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 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.
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_ufs(4),
generic fsck(1M),
generic mkfs(1M),
fs_ufs(4)
© 2004 The SCO Group, Inc. All rights reserved.
UnixWare 7 Release 7.1.4 - 25 April 2004