mkfs_xfs(1M) mkfs_xfs(1M)
mkfs_xfs - construct an XFS filesystem
mkfs_xfs [ -b subopt=value ] [ -d subopt[=value] ] [ -i subopt=value ]
[ -l subopt[=value] ] [ -n subopt[=value] ] [ -p protofile ] [ -q ]
[ -r subopt[=value] ] [ -C ] device
mkfs_xfs constructs an XFS filesystem by writing on a special file using
the values found in the arguments of the command line. It is invoked
automatically by mkfs(1M) when mkfs is given the -t xfs option, options
that are specific to XFS, or no options that are specific to EFS.
In its simplest (and most commonly used form), the size of the filesystem
is determined from the disk driver. As an example, to make a filesystem
on partition 7 (all of the useable portion of an option drive, normally)
on drive 7 on SCSI bus 0, with an internal log, use:
mkfs_xfs /dev/dsk/dks0d7s7
XFS filesystems are composed of a data section, a log section, and
optionally a real-time section. This separation can be accomplished
using the XLV volume manager to create a multi-subvolume volume, or by
embedding an internal log section in the data section. In the former
case, the device name is supplied as the final argument. In the latter
case a disk partition or XLV logical volume without a log subvolume can
contain the XFS filesystem, which is named by the -d name=special option
or by the final argument.
Each of the subopt=value elements in the argument list above can be given
as multiple comma-separated subopt=value suboptions if multiple
suboptions apply to the same option. Equivalently, each main option can
be given multiple times with different suboptions. For example, -l
internal,size=1000b and -l internal -l size=1000b are equivalent.
In the descriptions below, sizes are given in bytes, blocks, kilobytes,
or megabytes. Sizes are treated as hexadecimal if prefixed by 0x or 0X,
octal if prefixed by 0, or decimal otherwise. If suffixed with b then
the size is converted by multiplying it by the filesystem's block size.
If suffixed with k then the size is converted by multiplying it by 1024.
If suffixed with m then the size is converted by multiplying it by
1048576 (1024 * 1024). If suffixed with g then the size is converted by
multiplying it by 1073741824 (1024 * 1024 * 1024).
-b Block size options.
This option specifies the fundamental block size of the filesystem.
The valid suboptions are: log=value and size=value; only one can be
supplied. The block size is specified either as a base two
logarithm value with log=, or in bytes with size=. The default
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value is 4096 bytes (4 KB). The minimum value for block size is
512; the maximum is 65536 (64 KB).
-d Data section options.
These options specify the location, size, and other parameters of
the data section of the filesystem. The valid suboptions are:
agcount=value, agsize=value, file[=value], name=value, size=value,
sunit=value, swidth=value, su=value, sw=value, and
unwritten[=value].
The agcount suboption is used to specify the number of allocation
groups. The data section of the filesystem is divided into
allocation groups to improve the performance of XFS. More
allocation groups imply that more parallelism can be achieved when
allocating blocks and inodes. The minimum allocation group size is
16 MB; the maximum size is just under 4 GB. The data section of the
filesystem is divided into agcount allocation groups (default value
8, unless the filesystem is smaller than 128 MB or larger than 8
GB). Setting agcount to a very large number should be avoided,
since this causes an unreasonable amount of CPU time to be used when
the filesystem is close to full.
The agsize suboption is an alternative to using agcount. The
argument provided to agsize is the desired size of the allocation
group expressed in bytes (usually using the m or g suffixes). This
value must be a multiple of the filesystem block size, and must be
at least 16MB, and no more than 4GB, and may be automatically
adjusted to properly align with the stripe geometry. The agcount
suboption and the agsize suboption are mutually exclusive.
The name suboption can be used to specify the name of the special
file containing the filesystem. In this case, the log section must
be specified as internal (with a size, see the -l option below) and
there can be no real-time section. Either the block or character
special device can be supplied. An XLV logical volume with a log
subvolume cannot be supplied here. Note that the default log in
this case is an internal log with at least 1000 blocks, actual size
depending on the filesystem block size and the directory block size.
The file suboption is used to specify that the file given by the
name suboption is a regular file. The suboption value is either 0
or 1, with 1 signifying that the file is regular. This suboption is
used only to make a filesystem image (for instance, a miniroot
image). If the value is omitted then 1 is assumed.
The size suboption is used to specify the size of the data section.
This suboption is required if -d file[=1] is given. Otherwise, it
is only needed if the filesystem should occupy less space than the
size of the special file.
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The sunit suboption is used to specify the stripe unit for a RAID
device or XLV striped volume. The suboption value has to be
specified in 512-byte block units. Use the su suboption to specify
the stripe unit size in bytes. This suboption ensures that data
allocations will be stripe unit aligned when the current end of file
is being extended and the file size is larger than 512KB. Also
inode allocations and the internal log will be stripe unit aligned.
The su suboption is an alternative to using sunit. The su suboption
is used to specify the stripe unit for a RAID device or XLV/XVM
striped volume. The suboption value has to be specified in bytes,
(usually using the m or g suffixes). This value must be a multiple
of the filesystem block size.
The swidth suboption is used to specify the stripe width for a RAID
device or XLV striped volume. The suboption value has to be
specified in 512-byte block units. Use the sw suboption to specify
the stripe width size in bytes. This suboption is required if -d
sunit has been specified and it has to be a multiple of the -d sunit
suboption. The stripe width will be the preferred iosize returned
in the stat system call.
The sw suboption is an alternative to using swidth. The sw suboption
is used to specify the stripe width for a RAID device or XLV striped
volume. The suboption value is expressed as a multiplier of the
stripe unit, usually the same as the number of stripe members in the
XLV/XVM configuration, or data disks in a RAID device.
The unwritten suboption is used to specify whether unwritten extents
are flagged as such, or not. The suboption value is either 0 or 1,
with 1 signifying that unwritten extent flagging should occur. If
the suboption is omitted, unwritten extent flagging is enabled. If
unwritten extents are flagged, filesystem write performance will be
negatively affected for preallocated file extents, since extra
filesystem transactions are required to convert extent flags for the
range of the file written. This suboption should be disabled if the
filesystem needs to be used on operating system versions which do
not support the flagging capability.
-i Inode options.
This option specifies the inode size of the filesystem, and other
inode allocation parameters. The XFS inode contains a fixed-size
part and a variable-size part. The variable-size part, whose size
is affected by this option, can contain: directory data, for small
directories; attribute data, for small attribute sets; symbolic link
data, for small symbolic links; the extent list for the file, for
files with a small number of extents; and the root of a tree
describing the location of extents for the file, for files with a
large number of extents.
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The valid suboptions for specifying inode size are: log=value,
perblock=value, and size=value; only one can be supplied. The inode
size is specified either as a base two logarithm value with log=, in
bytes with size=, or as the number fitting in a filesystem block
with perblock=. The mininum (and default) value is 256 bytes. The
maximum value is 2048 (2 KB) subject to the restriction that the
inode size cannot exceed one half of the filesystem block size.
The option maxpct=value specifies the maximum percentage of space in
the filesystem that can be allocated to inodes. The default value
is 25%. Setting the value to 0 means that essentially all of the
filesystem can become inode blocks.
The option align[=value] is used to specify that inode allocation is
or is not aligned. The value is either 0 or 1, with 1 signifying
that inodes are allocated aligned. If the value is omitted, 1 is
assumed. The default is that inodes are aligned. Aligned inode
access is normally more efficient than unaligned access; alignment
must be established at the time the filesystem is created, since
inodes are allocated at that time. This option can be used to turn
off inode alignment when the filesystem needs to be mountable by a
version of IRIX that does not have the inode alignment feature (any
release of IRIX before 6.2, and IRIX 6.2 without XFS patches).
-l Log section options.
These options specify the location, size, and other parameters of
the log section of the filesystem. The valid suboptions are:
internal[=value] and size=value.
The internal suboption is used to specify that the log section is a
piece of the data section instead of being a separate part of an XLV
logical volume. The suboption value is either 0 or 1, with 1
signifying that the log is internal. If the value is omitted, 1 is
assumed.
The size suboption is used to specify the size of the log section.
This suboption is required if -l internal[=1] is given. Otherwise,
it is only needed if the log section of the filesystem should occupy
less space than the size of the special file. The size is specified
in bytes or blocks, with a b suffix meaning multiplication by the
filesystem block size, as described above. The overriding minimum
value for size is 512 blocks. With some combinations of filesystem
block size, inode size, and directory block size, the minimum log
size is larger than 512 blocks.
For a filesystem which is not contained in an XLV logical volume
with a log subvolume, the default is to make an internal log 1000
blocks long, or longer with some combinations of filesystem block
size, inode size, and directory block size.
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For a filesystem which is contained in a XLV striped logical volume,
the default internal log size is rounded up to a multiple of the
stripe unit size. In this case, the user specified size value must
be a multiple of the stripe unit size.
-n Naming options.
These options specify the version and size parameters for the naming
(directory) area of the filesystem. The valid suboptions are:
log=value, size=value, and version=value. The naming (directory)
version is 1 or 2, defaulting to 2 if unspecified. With version 2
directories, the directory block size can be any power of 2 size
from the filesystem block size up to 65536. The block size is
specified either as a base two logarithm value with log=, or in
bytes with size=. The default size value for version 2 directories
is 4096 bytes (4 KB), unless the filesystem block size is larger
than 4096, in which case the default value is the filesystem block
size. For version 1 directories the block size is the same as the
filesystem block size.
Note that you must use V1 directories in the rare case that your
filesystems are expected to be moved to computers running IRIX
releases older than IRIX 6.5.5. Such older releases of IRIX will
not be able to mount a filesystem created with V2 directories and
will issue the message "Wrong filesystem type: xfs" when a mount is
attempted.
-p protofile
If the optional -p protofile argument is given, mkfs_xfs uses
protofile as a prototype file and takes its directions from that
file. The blocks and inodes specifiers in the protofile are
provided for backwards compatibility, but are otherwise unused. The
prototype file contains tokens separated by spaces or newlines. A
sample prototype specification follows (line numbers have been added
to aid in the explanation):
1 /stand/diskboot
2 4872 110
3 d--777 3 1
4 usr d--777 3 1
5 sh ---755 3 1 /bin/sh
6 ken d--755 6 1
7 $
8 b0 b--644 3 1 0 0
9 c0 c--644 3 1 0 0
10 fifo p--644 3 1
11 slink l--644 3 1 /a/symbolic/link
12 : This is a comment line
13 $
14 $
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Line 1 is a dummy string. (It was formerly the bootfilename.) It
is present for backward compatibility; boot blocks are not used on
SGI systems.
Note that some string of characters must be present as the first
line of the proto file to cause it to be parsed correctly; the value
of this string is immaterial since it is ignored.
Line 2 contains two numeric values (formerly the numbers of blocks
and inodes). These are also merely for backward compatibility: two
numeric values must appear at this point for the proto file to be
correctly parsed, but their values are immaterial since they are
ignored.
Lines 3-11 tell mkfs_xfs about files and directories to be included
in this filesystem. Line 3 specifies the root directory. Lines 4-6
and 8-10 specifies other directories and files. Note the special
symbolic link syntax on line 11.
The $ on line 7 tells mkfs_xfs to end the branch of the filesystem
it is on, and continue from the next higher directory. It must be
the last character on a line. The colon on line 12 introduces a
comment; all characters up until the following newline are ignored.
Note that this means you cannot have a file in a prototype file
whose name contains a colon. The $ on lines 13 and 14 end the
process, since no additional specifications follow.
File specifications give the mode, the user ID, the group ID, and
the initial contents of the file. Valid syntax for the contents
field depends on the first character of the mode.
The mode for a file is specified by a 6-character string. The first
character specifies the type of the file. The character range is
-bcdpl to specify regular, block special, character special,
directory files, named pipes (fifos), and symbolic links,
respectively. The second character of the mode is either u or - to
specify setuserID mode or not. The third is g or - for the
setgroupID mode. The rest of the mode is a three digit octal number
giving the owner, group, and other read, write, execute permissions
(see chmod(1)).
Two decimal number tokens come after the mode; they specify the user
and group IDs of the owner of the file.
If the file is a regular file, the next token of the specification
can be a pathname from which the contents and size are copied. If
the file is a block or character special file, two decimal numbers
follow that give the major and minor device numbers. If the file is
a symbolic link, the next token of the specification is used as the
contents of the link. If the file is a directory, mkfs_xfs makes
the entries . and .. and then reads a list of names and
(recursively) file specifications for the entries in the directory.
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As noted above, the scan is terminated with the token $.
-q Quiet option.
Normally mkfs_xfs prints the parameters of the filesystem to be
constructed; the -q flag suppresses this.
-r Real-time section options.
These options specify the location, size, and other parameters of
the real-time section of the filesystem. The valid suboptions are:
extsize=value and size=value.
The extsize suboption is used to specify the size of the blocks in
the real-time section of the filesystem. This size must be a
multiple of the filesystem block size. The minimum allowed value is
the filesystem block size or 4 KB (whichever is larger); the default
value is the stripe width for striped volumes or 64 KB for nonstriped
volumes; the maximum allowed value is 1 GB. The real-time
extent size should be carefully chosen to match the parameters of
the physical media used.
The size suboption is used to specify the size of the real-time
section. This suboption is only needed if the real-time section of
the filesystem should occupy less space than the size of the XLV
real-time subvolume.
-C Disable overlapping partition/volume checks.
By default mkfs_xfs checks to see if the destination partition or
logical volume overlaps any mounted or reserved partitions in the
system. If an overlap or mount conflict is found, the user will be
notified and prevented from potentially corrupting the existing
data. For systems with a large number of disks, this additional
checking may add noticable overhead to the command's execution time.
For situations where command performance is necessary, this switch
may be used to disable the safeguards. Due to the potential for
user-error causing corrupted filesystems or other on-disk data
corruption, we strongly discourage use of this switch in normal
operation.
mkfs(1M), mkfs_efs(1M).
With a prototype file, it is not possible to specify hard links.
PPPPaaaaggggeeee 7777 [ Back ]
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