SunOS man pages : mkfs_ufs (1)
Maintenance Commands mkfs_ufs(1M)
NAME
mkfs_ufs - construct a ufs file system
SYNOPSIS
mkfs -F ufs [ generic_options ] [
-o FSType_specific_options ] raw_device_file [ size ]
DESCRIPTION
The ufs-specific module of mkfs builds a ufs file system
with a root directory and a lost+found directory (see
fsck(1M))
The ufs-specific mkfs is rarely run directly; use the
newfs(1M) command instead.
raw_device_file indicates the disk partition to write on
unless the -o N option has been specified, or either the -V
or -m generic options are passed from the generic mkfs
module. size specifies the number of sectors in the file
system. This argument must follow the raw_device_file argu-
ment and is required (even with -o N), unless the -V or
-m generic options are specified.
generic_options are supported by the generic mkfs command.
See mkfs(1M) for a description of these options.
OPTIONS
The following options are supported:
-o Use one or more of the following values separated by
commas (with no intervening spaces) to specify ufs-
specific options:
N Print out the file system parameters without actu-
ally creating the file system.
nsect=n
The number of sectors per track on the disk. The
default is 32.
ntrack=n
The number of tracks per cylinder on the disk. The
default is 16.
bsize=n
Logical block size, either 4096 or 8192. The default
is 8192. The sun4u architecture does not support the
4096 block size.
fragsize=n
The smallest amount of disk space in bytes to allocate
to a file. The smallest amout of disk space in bytes
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Maintenance Commands mkfs_ufs(1M)
to allocate to a file. If the logical block size is
4096, legal values are 512, 1024, 2048, and 4096.
When the logical block size is 8192, legal values are
1024, 2048, 4096, and 8192. The default value is
1024.
cgsize=n
The number of cylinders per cylinder group (ranging
from 16 to 256).
The default is calculated by dividing the number of
sectors in the file system by the number of sectors in
a gigabyte, and then multiplying the result by 32. The
default value will always be between 16 and 256. The
per-cylinder-group meta data must fit in a space no
larger than that available in one logical file system
block. If too large a cgsize is requested, it is
decreased by the minimum amount necessary.
free=n
The minimum percentage of free space to maintain in
the file system. This space is off-limits to normal
users. Once the file system is filled to this thres-
hold, only the superuser can continue writing to the
file system. This parameter can be subsequently
changed using the tunefs(1M) command. The default is
10%.
rps=n The rotational speed of the disk, in revolutions per
second. The default is 60.
nbpi=n
The number of bytes per inode, which specifies the
density of inodes in the file system. The number is
divided into the total size of the file system to
determine the fixed number of inodes to create. It
should reflect the expected average size of files 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 default is 2048.
opt=a Space or time optimization preference; s specifies
optimization for space, t specifies optimization for
time. The default is t. This parameter may be subse-
quently changed with the tunefs(1M) command.
apc=n The number of alternates per cylinder to reserve for
bad block replacement (SCSI devices only). The default
is 0.
gap=n Rotational delay. The expected time (in milliseconds)
to service a transfer completion interrupt and ini-
tiate a new transfer on the same disk. The value is
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Maintenance Commands mkfs_ufs(1M)
used to decide how much rotational spacing to place
between successive blocks in a file. This parameter
can be subsequently changed using the tunefs(1M) com-
mand. The default is disk-type dependent.
nrpos=n
The number of different rotational positions in which
to divide a cylinder group. The default is 8.
maxcontig=n
The maximum number of blocks, belonging to one file,
that will be allocated contiguously before inserting a
rotational delay. For a 4K file system, the default is
14; for an 8K file system it is 7. This parameter can
be subsequently changed using the tunefs(1M) command.
This parameter also controls clustering. Regardless
of the value of gap, 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(1M).
Alternatively, parameters can be entered as a list of
space-separated values (without keywords) whose meaning is
positional. In this case, the -o option is omitted and the
list follows the size operand. This is the way newfs
passes the parameters to mkfs.
OPERANDS
The following operands are supported:
raw_device_file
The disk partition on which to write.
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWcsu |
|_____________________________|_____________________________|
SEE ALSO
fsck(1M), mkfs(1M), newfs(1M), tunefs(1M), dir_ufs(4),
fs_ufs(4), attributes(5)
DIAGNOSTICS
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Maintenance Commands mkfs_ufs(1M)
The following error message occurs typically on very high
density disks. On such disks, the file system structure can-
not encode the proper disk layout information, resulting in
suboptimal performance.
Warning: insufficient space in super block for
rotational layout tables with nsect sblock.fs_nsect
and ntrak sblock.fs_ntrak. (File system performance may be impaired.)
The following error message occurs if a user request for
inodes or bytes (with the nbpi keyword) and the disk
geometry results in a situation in which the last truncated
cylinder group cannot contain the correct number of data
blocks; some disk space is wasted.
Warning: inode blocks/cyl group (grp) >= data blocks (num) in last cylinder
The following error message occurs if the user parameters
and disk geometry conflict; some disk space is lost. A pos-
sible cause is the specified size being smaller than the
partition size.
Warning: num sector(s) in last cylinder group unallocated
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