mkfs_ufs(1M) System Administration Commands mkfs_ufs(1M)NAMEmkfs_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 on which to create the new
file system. If the -o N, -V, or -m options are specified, the
raw_device_file is not actually modified. size specifies the number of
disk sectors in the file system, where a disk sector is usually 512
bytes. This argument must follow the raw_device_file argument 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 generic options are supported:
-m Print the command line that was used to create the
existing file system.
-V Print the current mkfs command line.
OPTIONS
The following UFS-specific options are supported:
-o
Use one or more of the following values separated by commas (with
no intervening spaces) to specify UFS-specific options:
apc=n
The number of alternate sectors per cylinder to reserve for bad
block replacement for SCSI devices only. The default is 0.
This option is not applicable for disks with EFI labels and is
ignored.
bsize=n
The logical block size of the file system in bytes, either 4096
or 8192. The default is 8192. The sun4u architecture does not
support the 4096 block size.
calcbinsb
Sends to stdout a binary (machine-readable) version of the
superblock that would be used to create a file system with the
specified configuration parameters.
calcsb
Sends to stdout a human-readable version of the superblock that
would be used to create a file system with the specified con‐
figuration parameters.
cgsize=n
The number of cylinders per cylinder group, ranging from 16 to
256. The default is calculated by dividing the number of sec‐
tors in the file system by the number of sectors in a gigabyte.
Then, the result is multiplied by 32. The default value is
always between 16 and 256.
The per-cylinder-group meta data must fit in a space no larger
than what is available in one logical file system block. If too
large a cgsize is requested, it is changed by the minimum
amount necessary.
fragsize=n
The smallest amount of disk space in bytes that can be allo‐
cated to a file. fragsize must be a power of 2 divisor of
bsize, where:
bsize / fragsize is 1, 2, 4, or 8.
This means that if the logical block size is 4096, legal values
for fragsize 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.
For file systems greater than 1 terabyte or for file systems
created with the mtb=y option, fragsize is forced to match
block size (bsize).
free=n
The minimum percentage of free space to maintain in the file
system between 0% and 99%, inclusively. This space is off-lim‐
its to users. Once the file system is filled to this threshold,
only the superuser can continue writing to the file system.
The default is ((64 Mbytes/partition size) * 100), rounded down
to the nearest integer and limited between 1% and 10%, inclu‐
sively.
This parameter can be subsequently changed using the tunefs(1M)
command.
gap=n
Rotational delay. This option is obsolete in the Solaris 10
release. The value is always set to 0, regardless of the input
value.
maxcontig=n
The maximum number of logical blocks, belonging to one file,
that are allocated contiguously. The default is calculated as
follows:
maxcontig = disk drive maximum transfer size / disk block size
If the disk drive's maximum transfer size cannot be determined,
the default value for maxcontig is calculated from kernel
parameters as follows:
If maxphys is less than ufs_maxmaxphys, which is typically 1
Mbyte, then maxcontig is set to maxphys. Otherwise, maxcontig
is set to ufs_maxmaxphys.
You can set maxcontig to any positive integer value.
The actual value will be the lesser of what has been specified
and what the hardware supports.
You can subsequently change this parameter by using tunefs(1M).
mtb=y
Set the parameters of the file system to allow eventual growth
to over a terabyte in total file system size. This option sets
fragsize to be the same as bsize, and sets nbpi to 1 Mbyte,
unless the -i option is used to make it even larger. If you
explicitly set the fragsize or nbpi parameters to values that
are incompatible with this option, the user-supplied value of
fragsize or nbpi is ignored.
N
Print out the file system parameters that would be used to cre‐
ate the file system without actually creating the file system.
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 number of inodes to
create.
This value 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.
The number of inodes can increase if the file system is
expanded with the growfs command.
nrpos=n
The number of different rotational positions in which to divide
a cylinder group. The default is 8.
This option is not applicable for disks with EFI labels and is
ignored.
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.
This option is not applicable for disks with EFI labels and is
ignored.
opt=s|t
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. The default is time.
This parameter can be subsequently changed with the tunefs(1M)
command.
rps=n
The rotational speed of the disk, in revolutions per second.
The default is 60.
Note that you specify rps for mkfs and rpm for newfs.
This option is not applicable for disks with EFI labels and is
ignored.
Alternatively, parameters can be entered as a list of space-sepa‐
rated 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 attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWcsu │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOfsck(1M), mkfs(1M), newfs(1M), tunefs(1M), dir_ufs(4), attributes(5),
ufs(7FS)DIAGNOSTICS
The following error message typically occurs with very high density
disks. On such disks, the file system structure cannot encode the
proper disk layout information. However, such disks have enough onboard
intelligence to make up for any layout deficiencies, so there is no
actual impact on performance. The warning that performance might be
impaired can be safely ignored.
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 when the disk geometry results in a
situation where 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
If there is only one cylinder group and if the above condition holds
true, mkfs fails with the following error:
File system creation failed. There is only one cylinder group and that is
not even big enough to hold the inodes.
The following error message occurs when the best calculated file system
layout is unable to include the last few sectors in the last cylinder
group. This is due to the interaction between how much space is used
for various pieces of meta data and the total blocks available in a
cylinder group. Modifying nbpi and cpg might reduce this number, but it
is rarely worth the effort.
Warning: num sector(s) in last cylinder group unallocated
NOTES
You can use lofiadm to create a file that appears to the mkfs command
(for example, mkfs_pcfs or mkfs_ufs) as a raw device. You can then use
the mkfs command to create a file system on that device. See lofi‐
adm(1M) for examples of creating a UFS and a PC (FAT) file system on a
device created by lofiadm.
Both the block and character devices, such as devices in /dev/dsk and
/dev/rdsk, must be available prior to running the mkfs command.
SunOS 5.10 8 Mar 2006 mkfs_ufs(1M)
