Manual page for MKFS(8)
mkfs - construct a file system
SYNOPSIS
/usr/etc/mkfs
[
-N
]
special size
[ nsect ]
[ ntrack ]
[ blksize ]
[ fragsize ]
[ ncpg ]
[ minfree ]
[ rps ]
[ nbpi ]
[ opt ]
[ apc ]
[ rot ]
[ nrpos ]
[ maxcontig ]
DESCRIPTION
Note:
file systems are normally created with the
newfs.8
command.
mkfs
constructs a file system by writing on the special file
special
unless the
-N
flag has been specified.
special
must be specified as a raw device and disk partition.
For example, to create a file system on
sd0,
specify
/dev/rsd0[a-h],
where
a-h
is the disk partition.
The numeric
size
specifies the number of sectors in the file system.
mkfs
builds a file system with a root directory and a lost+found
directory (see
fsck.8
The number of inodes is calculated as a
function of the file system size.
No boot program is initialized by
mkfs
(see
newfs.8
You must be super-user to use this command.
OPTIONS
- -N
-
Print out the file system parameters without actually creating the file
system.
The following arguments allow fine tune control over the
parameters of the file system.
- nsect
-
The number of sectors per track on the disk. The default is
32.
- ntrack
-
The number of tracks per cylinder on the disk. The default is
16.
- blksize
-
The primary block size for files on the file system.
It must be a power of two, currently selected from
4096
or
8192
(the default).
- fragsize
-
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.
- ncpg
-
The number of disk cylinders per cylinder group.
The default is
16.
- minfree
-
The minimum percentage of free disk space allowed.
Once the file system capacity reaches this threshold, only
the super-user is allowed to allocate disk blocks.
The default value is
10%.
- rps
-
The rotational speed of the disk, in revolutions per second.
The default is
60.
- nbpi
-
The number of bytes for which one inode block is allocated.
This parameter is
currently set at
one
inode block for every 2048 bytes.
- opt
-
Space or time optimization preference;
s
specifies optimization for space,
t
specifies optimization for time. The default is
t.
- apc
-
The number of alternates per cylinder (SCSI devices only).
The default is
0.
- rot
-
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
1.
Note:
in earlier releases
mkfs
tried to guess what the right value for this parameter by querying the
controller type. Since
mkfs
is a more primitive interface, this query has been moved into
newfs.
mkfs
now does exactly what you tell it to do.
- nrpos
-
The number of distinguished rotational positions.
The default is
8.
- maxcontig
-
The maximum number of blocks that will be allocated contiguously before
inserting a rotational delay. The default is
1.
Note: This parameter also controls
clustering. Regardless of the value of rotdelay,
clustering is enabled only when maxcontig is greater than 1.
Clustering allows higher I/O rates for sequential
I/O and is described in
tunefs.8
Users with special demands for their file systems are referred to
the paper cited below for a discussion of the tradeoffs in using
different configurations.
SEE ALSO
dir.5
fs.5
fsck.8
newfs.8
tunefs.8
[a manual with the abbreviation ADMIN]
McKusick, Joy, Leffler;
A Fast File System for UNIX
NOTES
newfs.8
is preferred for most routine uses.
Created by unroff & hp-tools.
© somebody (See intro for details). All Rights Reserved.
Last modified 11/5/97