.SH NAME
mkfs.xfs \- construct an XFS filesystem
.SH SYNOPSIS
-.nf
-\f3mkfs.xfs\f1 [ \f3\-b\f1 subopt=value ] [ \f3\-d\f1 subopt[=value] ]
- [ \f3\-i\f1 subopt=value ] [ \f3\-l\f1 subopt[=value] ]
- [ \f3\-n\f1 subopt[=value] ] [ \f3\-p\f1 protofile ] [ \f3\-q\f1 ]
- [ \f3\-r\f1 subopt[=value] ] [ \f3\-C\f1 ] [ \f3\-L\f1 label ] device
-.fi
+.B mkfs.xfs
+[
+.B \-b
+.I block_size
+] [
+.B \-m
+.I global_metadata_options
+] [
+.B \-d
+.I data_section_options
+] [
+.B \-f
+] [
+.B \-i
+.I inode_options
+] [
+.B \-l
+.I log_section_options
+] [
+.B \-n
+.I naming_options
+] [
+.B \-p
+.I protofile
+] [
+.B \-q
+] [
+.B \-r
+.I realtime_section_options
+] [
+.B \-s
+.I sector_size
+] [
+.B \-L
+.I label
+] [
+.B \-N
+] [
+.B \-K
+]
+.I device
+.br
+.B mkfs.xfs \-V
.SH DESCRIPTION
-.I mkfs.xfs
+.B 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 \f2mkfs\f1(8) when \f2mkfs\f1 is
-given the \f3\-t xfs\f1 option.
+It is invoked automatically by
+.BR mkfs (8)
+when it is given the
+.B \-t xfs
+option.
.PP
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 with an internal log on the first partition on the first
SCSI disk, use:
-.PP
-.nf
- mkfs.xfs /dev/sda1
-.fi
+.IP
+.B mkfs.xfs /dev/sda1
.PP
The metadata log can be placed on another device to reduce the number
of disk seeks. To create a filesystem on the first partition on the
-first SCSI disk with a 10000 block log located on the first partition
+first SCSI disk with a 10MiB log located on the first partition
on the second SCSI disk, use:
-.PP
-.nf
- mkfs.xfs -l logdev=/dev/sdb1,size=10000b /dev/sda1
-.fi
+.RS
+.HP
+.B mkfs.xfs\ \-l\ logdev=/dev/sdb1,size=10m /dev/sda1
+.RE
.PP
Each of the
-.I subopt=value
+.I option
elements in the argument list above can be given as multiple comma-separated
-.I 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,
-.B \-l internal,size=10000b
+.B \-l internal,size=10m
and
-.B \-l internal \-l size=10000b
+.B \-l internal \-l size=10m
are equivalent.
.PP
-In the descriptions below, sizes are given in bytes, blocks, kilobytes,
-or megabytes.
+In the descriptions below, sizes are given in sectors, bytes, blocks,
+kilobytes, megabytes, gigabytes, etc.
Sizes are treated as hexadecimal if prefixed by 0x or 0X,
octal if prefixed by 0, or decimal otherwise.
-If suffixed with \f3b\f1 then the size is converted by multiplying it
-by the filesystem's block size.
-If suffixed with \f3k\f1 then the size is converted by multiplying it by 1024.
-If suffixed with \f3m\f1 then the size is converted by multiplying it by
-1048576 (1024 * 1024).
-If suffixed with \f3g\f1 then the size is converted by multiplying it by
-1073741824 (1024 * 1024 * 1024).
-.TP
+The following lists possible multiplication suffixes:
+.RS
+.PD 0
+.HP
+.BR s "\ \-\ multiply by sector size (default = 512, see " \-s
+option below).
+.HP
+.BR b "\ \-\ multiply by filesystem block size (default = 4K, see " \-b
+option below).
+.HP
+.BR k "\ \-\ multiply by one kilobyte (1,024 bytes)."
+.HP
+.BR m "\ \-\ multiply by one megabyte (1,048,576 bytes)."
+.HP
+.BR g "\ \-\ multiply by one gigabyte (1,073,741,824 bytes)."
+.HP
+.BR t "\ \-\ multiply by one terabyte (1,099,511,627,776 bytes)."
+.HP
+.BR p "\ \-\ multiply by one petabyte (1,024 terabytes)."
+.HP
+.BR e "\ \-\ multiply by one exabyte (1,048,576 terabytes)."
+.PD
+.RE
+.PP
+When specifying parameters in units of sectors or filesystem blocks, the
+.B \-s
+option or the
.B \-b
-Block size options.
-.IP
+option first needs to be added to the command line.
+Failure to specify the size of the units will result in illegal value errors
+when parameters are quantified in those units.
+.PP
+Many feature options allow an optional argument of 0 or 1, to explicitly
+disable or enable the functionality.
+.SH OPTIONS
+.TP
+.BI \-b " block_size_options"
This option specifies the fundamental block size of the filesystem.
-The valid suboptions are:
+The valid
+.I block_size_options
+are:
.BI log= value
-and
-\f3size=\f1\f2value\f1;
-only one can be supplied.
+or
+.BI size= value
+and only one can be supplied.
The block size is specified either as a base two logarithm value with
.BR log= ,
or in bytes with
.BR size= .
-The default value is 4096 bytes (4 KB) on systems with a 4KB pagesize.
-The minimum value for block size is 512; the maximum is 65536 (64 KB).
-XFS on Linux currently only supports pagesize blocks.
-.TP
-.B \-d
-Data section options.
+The default value is 4096 bytes (4 KiB), the minimum is 512, and the
+maximum is 65536 (64 KiB).
.IP
-These options specify the location, size, and other parameters of the
-data section of the filesystem.
-The valid suboptions are:
-\f3agcount=\f1\f2value\f1,
-\f3agsize=\f1\f2value\f1,
-\f3file\f1[\f3=\f1\f2value\f1],
-\f3name=\f1\f2value\f1,
-\f3size=\f1\f2value\f1,
-\f3sunit=\f1\f2value\f1,
-\f3swidth=\f1\f2value\f1,
-\f3su=\f1\f2value\f1,
-\f3sw=\f1\f2value\f1,
-and
-\f3unwritten\f1[\f3=\f1\f2value\f1].
+To specify any options on the command line in units of filesystem blocks, this
+option must be specified first so that the filesystem block size is
+applied consistently to all options.
.IP
-The
-.B 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.
+Although
+.B mkfs.xfs
+will accept any of these values and create a valid filesystem,
+XFS on Linux can only mount filesystems with pagesize or smaller blocks.
+.TP
+.BI \-m " global_metadata_options"
+These options specify metadata format options that either apply to the entire
+filesystem or aren't easily characterised by a specific functionality group. The
+valid
+.I global_metadata_options
+are:
+.RS 1.2i
+.TP
+.BI crc= value
+This is used to create a filesystem which maintains and checks CRC information
+in all metadata objects on disk. The value is either 0 to disable the feature,
+or 1 to enable the use of CRCs.
+.IP
+CRCs enable enhanced error detection due to hardware issues, whilst the format
+changes also improves crash recovery algorithms and the ability of various tools
+to validate and repair metadata corruptions when they are found. The CRC
+algorithm used is CRC32c, so the overhead is dependent on CPU architecture as
+some CPUs have hardware acceleration of this algorithm. Typically the overhead
+of calculating and checking the CRCs is not noticeable in normal operation.
+.IP
+By default,
+.B mkfs.xfs
+will enable metadata CRCs.
+.TP
+.BI finobt= value
+This option enables the use of a separate free inode btree index in each
+allocation group. The value is either 0 to disable the feature, or 1 to create
+a free inode btree in each allocation group.
+.IP
+The free inode btree mirrors the existing allocated inode btree index which
+indexes both used and free inodes. The free inode btree does not index used
+inodes, allowing faster, more consistent inode allocation performance as
+filesystems age.
+.IP
+By default,
+.B mkfs.xfs
+will create free inode btrees for filesystems created with the (default)
+.B \-m crc=1
+option set. When the option
+.B \-m crc=0
+is used, the free inode btree feature is not supported and is disabled.
+.TP
+.BI uuid= value
+Use the given value as the filesystem UUID for the newly created filesystem.
+The default is to generate a random UUID.
+.TP
+.BI rmapbt= value
+This option enables the creation of a reverse-mapping btree index in each
+allocation group. The value is either 0 to disable the feature, or 1 to
+create the btree.
+.IP
+The reverse mapping btree maps filesystem blocks to the owner of the
+filesystem block. Most of the mappings will be to an inode number and an
+offset, though there will also be mappings to filesystem metadata. This
+secondary metadata can be used to validate the primary metadata or to
+pinpoint exactly which data has been lost when a disk error occurs.
+.IP
+By default,
+.B mkfs.xfs
+will not create reverse mapping btrees. This feature is only available
+for filesystems created with the (default)
+.B \-m crc=1
+option set. When the option
+.B \-m crc=0
+is used, the reverse mapping btree feature is not supported and is disabled.
+.RE
+.TP
+.BI \-d " data_section_options"
+These options specify the location, size, and other parameters of the
+data section of the filesystem. The valid
+.I data_section_options
+are:
+.RS 1.2i
+.TP
+.BI agcount= value
+This 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 MiB; the maximum size is just under 1 TiB.
The data section of the filesystem is divided into
-.I agcount
-allocation groups (default value 8, unless the filesystem is smaller
-than 128 MB or larger than 8 GB).
-Setting
-.I 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.
-.IP
-The
-.B agsize
-suboption is an alternative to using
-.B agcount.
-The argument provided to
-.B agsize
+.I value
+allocation groups (default value is scaled automatically based
+on the underlying device size).
+.TP
+.BI agsize= value
+This is an alternative to using the
+.B agcount
+suboption. The
+.I value
is the desired size of the allocation group expressed in bytes
-(usually using the \f3m\f1 or \f3g\f1 suffixes).
+(usually using the
+.BR 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
+must be at least 16MiB, and no more than 1TiB, and may
be automatically adjusted to properly align with the stripe geometry.
The
.B agcount
-suboption and the
+and
.B agsize
-suboption are mutually exclusive.
-.IP
-The
-.B 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
+suboptions are mutually exclusive.
+.TP
+.BI name= value
+This can be used to specify the name of the special file containing
+the filesystem. In this case, the log section must be specified as
.B internal
(with a size, see the
.B \-l
option below) and there can be no real-time section.
-.IP
-The
-.B file
-suboption is used to specify that the file given by the
+.TP
+.BI file[= value ]
+This is used to specify that the file given by the
.B 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.
-If the value is omitted then 1 is assumed.
-.IP
-The
-.B size
-suboption is used to specify the size of the data section.
-This suboption is required if
+suboption is a regular file. The
+.I value
+is either 0 or 1, with 1 signifying that the file is regular. This
+suboption is used only to make a filesystem image. If the
+.I value
+is omitted then 1 is assumed.
+.TP
+.BI size= value
+This is used to specify the size of the data section. This suboption
+is required if
.B \-d file[=1]
-is given.
-Otherwise, it is only needed if the filesystem should occupy
+is given. Otherwise, it is only needed if the filesystem should occupy
less space than the size of the special file.
-.IP
-The
-.B sunit
-suboption is used to specify the stripe unit for a RAID device or a
-logical volume.
-The suboption value has to be specified in 512-byte block units.
-Use the
-.B 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.
-.IP
-The
+.TP
+.BI sunit= value
+This is used to specify the stripe unit for a RAID device or a
+logical volume. The
+.I value
+has to be specified in 512-byte block units. Use the
.B su
-suboption is an alternative to using
+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 512KiB. Also inode allocations and the internal log will be
+stripe unit aligned.
+.TP
+.BI su= value
+This is an alternative to using
.B sunit.
The
.B su
suboption is used to specify the stripe unit for a RAID device or a
-striped logical volume.
-The suboption value has to be specified in bytes,
-(usually using the \f3m\f1 or \f3g\f1 suffixes).
-This value must be a multiple of the filesystem block size.
-.IP
-The
-.B swidth
-suboption is used to specify the stripe width for a RAID device or a
-striped logical volume.
-The suboption value has to be specified in 512-byte block units.
-Use the
+striped logical volume. The
+.I value
+has to be specified in bytes, (usually using the
+.BR m " or " g
+suffixes). This
+.I value
+must be a multiple of the filesystem block size.
+.TP
+.BI swidth= value
+This is used to specify the stripe width for a RAID device or a
+striped logical volume. The
+.I value
+has to be specified in 512-byte block units. Use the
.B sw
suboption to specify the stripe width size in bytes.
This suboption is required if
.B \-d sunit
-has been specified and it has to be a multiple of the
-.B \-d sunit
+has been specified and it has to be a multiple of the
+.B \-d sunit
suboption.
-The stripe width will be the preferred iosize returned in the
-.IR stat (2)
-system call.
-.IP
-The
-.B sw
+.TP
+.BI sw= value
suboption is an alternative to using
.B swidth.
The
.B sw
suboption is used to specify the stripe width for a RAID device or
-striped logical volume.
-The suboption value is expressed as a multiplier of the stripe unit,
+striped logical volume. The
+.I value
+is expressed as a multiplier of the stripe unit,
usually the same as the number of stripe members in the logical
volume configuration, or data disks in a RAID device.
.IP
When a filesystem is created on a logical volume device,
-.I mkfs.xfs
-will automatically query the logical volume for appropriate
+.B mkfs.xfs
+will automatically query the logical volume for appropriate
.B sunit
and
.B swidth
values.
-.IP
-The
-.B 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.
.TP
-.B \-i
-Inode options.
-.IP
+.BI noalign
+This option disables automatic geometry detection and creates the filesystem
+without stripe geometry alignment even if the underlying storage device provides
+this information.
+.RE
+.TP
+.B \-f
+Force overwrite when an existing filesystem is detected on the device.
+By default,
+.B mkfs.xfs
+will not write to the device if it suspects that there is a filesystem
+or partition table on the device already.
+.TP
+.BI \-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.
and the root of a tree describing the location of extents for the file,
for files with a large number of extents.
.IP
-The valid suboptions for specifying inode size are:
-\f3log=\f1\f2value\f1,
-\f3perblock=\f1\f2value\f1,
-and
-\f3size=\f1\f2value\f1;
-only one can be supplied.
-The inode size is specified either as a base two logarithm value with
-.BR log= ,
+The valid
+.I inode_options
+are:
+.RS 1.2i
+.TP
+.BI size= value " | log=" value " | perblock=" value
+The inode size is specified either as a
+.I value
in bytes with
.BR size= ,
+a base two logarithm
+.I value
+with
+.BR log= ,
or as the number fitting in a filesystem block with
.BR perblock= .
-The mininum (and default) value is 256 bytes.
-The maximum value is 2048 (2 KB) subject to the restriction that
+The minimum (and default)
+.I value
+is 256 bytes without crc, 512 bytes with crc enabled.
+The maximum
+.I value
+is 2048 (2 KiB) subject to the restriction that
the inode size cannot exceed one half of the filesystem block size.
.IP
-The option \f3maxpct=\f1\f2value\f1 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.
+XFS uses 64-bit inode numbers internally; however, the number of
+significant bits in an inode number
+is affected by filesystem geometry. In
+practice, filesystem size and inode size are the predominant factors.
+The Linux kernel (on 32 bit hardware platforms) and most applications
+cannot currently handle inode numbers greater than 32 significant bits,
+so if no inode size is given on the command line,
+.B mkfs.xfs
+will attempt to choose a size
+such that inode numbers will be < 32 bits. If an inode size
+is specified, or if a filesystem is sufficiently large,
+.B mkfs.xfs
+will warn if this will create inode numbers > 32 significant
+bits.
+.TP
+.BI maxpct= value
+This specifies the maximum percentage of space in the filesystem that
+can be allocated to inodes. The default
+.I value
+is 25% for filesystems under 1TB, 5% for filesystems under 50TB and 1%
+for filesystems over 50TB.
+.IP
+In the default inode allocation mode, inode blocks are chosen such
+that inode numbers will not exceed 32 bits, which restricts the inode
+blocks to the lower portion of the filesystem. The data block
+allocator will avoid these low blocks to accommodate the specified
+maxpct, so a high value may result in a filesystem with nothing but
+inodes in a significant portion of the lower blocks of the filesystem.
+(This restriction is not present when the filesystem is mounted with
+the
+.I "inode64"
+option on 64-bit platforms).
+.IP
+Setting the value to 0 means that essentially all of the filesystem
+can become inode blocks, subject to inode32 restrictions.
.IP
-The option
+This value can be modified with
+.IR xfs_growfs(8) .
+.TP
.BI 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.
+This is used to specify that inode allocation is or is not aligned. The
+.I value
+is either 0 or 1, with 1 signifying that inodes are allocated aligned.
+If the
+.I 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.
that does not have the inode alignment feature
(any release of IRIX before 6.2, and IRIX 6.2 without XFS patches).
.TP
-.B \-l
-Log section options.
-.IP
+.BI attr= value
+This is used to specify the version of extended attribute inline
+allocation policy to be used. By default, this is 2, which uses an
+efficient algorithm for managing the available inline inode space
+between attribute and extent data.
+.IP
+The previous version 1, which has fixed regions for attribute and
+extent data, is kept for backwards compatibility with kernels older
+than version 2.6.16.
+.TP
+.BI projid32bit[= value ]
+This is used to enable 32bit quota project identifiers. The
+.I value
+is either 0 or 1, with 1 signifying that 32bit projid are to be enabled.
+If the value is omitted, 1 is assumed. (This default changed
+in release version 3.2.0.)
+.TP
+.BI sparse[= value ]
+Enable sparse inode chunk allocation. The
+.I value
+is either 0 or 1, with 1 signifying that sparse allocation is enabled.
+If the value is omitted, 1 is assumed. Sparse inode allocation is
+disabled by default. This feature is only available for filesystems
+formatted with
+.B \-m crc=1.
+.IP
+When enabled, sparse inode allocation allows the filesystem to allocate
+smaller than the standard 64-inode chunk when free space is severely
+limited. This feature is useful for filesystems that might fragment free
+space over time such that no free extents are large enough to
+accommodate a chunk of 64 inodes. Without this feature enabled, inode
+allocations can fail with out of space errors under severe fragmented
+free space conditions.
+.RE
+.TP
+.BI \-l " log_section_options"
These options specify the location, size, and other parameters of the
-log section of the filesystem.
-The valid suboptions are:
+log section of the filesystem. The valid
+.I log_section_options
+are:
+.RS 1.2i
+.TP
.BI internal[= value ]
+This is used to specify that the log section is a piece of the data
+section instead of being another device or logical volume. The
+.I value
+is either 0 or 1, with 1 signifying that the log is internal. If the
+.I value
+is omitted, 1 is assumed.
+.TP
+.BI logdev= device
+This is used to specify that the log section should reside on the
+.I device
+separate from the data section. The
+.B internal=1
and
-\f3size=\f1\f2value\f1.
-.IP
-The
-.B internal
-suboption is used to specify that the log section is a piece of
-the data section instead of being another device or 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.
-.IP
-The
-.B size
-suboption is used to specify the size of the log section.
+.B logdev
+options are mutually exclusive.
+.TP
+.BI size= value
+This is used to specify the size of the log section.
.IP
-If the log is contained within the data section and
+If the log is contained within the data section and
.B size
isn't specified,
-.I mkfs.xfs
+.B mkfs.xfs
will try to select a suitable log size depending
on the size of the filesystem. The actual logsize depends on the
filesystem block size and the directory block size.
.IP
Otherwise, the
.B size
-option 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 \f3b\f1 suffix
-meaning multiplication by the filesystem block size, as described above.
-The overriding minimum value for size is 512 blocks.
+suboption is only needed if the log section of the filesystem
+should occupy less space than the size of the special file. The
+.I value
+is specified in bytes or blocks, with a
+.B 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.
.TP
-.B \-n
-Naming options.
+.BI version= value
+This specifies the version of the log. The current default is 2,
+which allows for larger log buffer sizes, as well as supporting
+stripe-aligned log writes (see the sunit and su options, below).
+.IP
+The previous version 1, which is limited to 32k log buffers and does
+not support stripe-aligned writes, is kept for backwards compatibility
+with very old 2.4 kernels.
+.TP
+.BI sunit= value
+This specifies the alignment to be used for log writes. The
+.I value
+has to be specified in 512-byte block units. Use the
+.B su
+suboption to specify the log stripe unit size in bytes.
+Log writes will be aligned on this boundary,
+and rounded up to this boundary.
+This gives major improvements in performance on some configurations
+such as software RAID5 when the
+.B sunit
+is specified as the filesystem block size.
+The equivalent byte value must be a multiple of the filesystem block
+size. Version 2 logs are automatically selected if the log
+.B sunit
+suboption is specified.
.IP
+The
+.B su
+suboption is an alternative to using
+.B sunit.
+.TP
+.BI su= value
+This is used to specify the log stripe. The
+.I value
+has to be specified in bytes, (usually using the
+.BR s " or " b
+suffixes). This value must be a multiple of the filesystem block size.
+Version 2 logs are automatically selected if the log
+.B su
+suboption is specified.
+.TP
+.BI lazy-count= value
+This changes the method of logging various persistent counters
+in the superblock. Under metadata intensive workloads, these
+counters are updated and logged frequently enough that the superblock
+updates become a serialization point in the filesystem. The
+.I value
+can be either 0 or 1.
+.IP
+With
+.BR lazy-count=1 ,
+the superblock is not modified or logged on every change of the
+persistent counters. Instead, enough information is kept in
+other parts of the filesystem to be able to maintain the persistent
+counter values without needed to keep them in the superblock.
+This gives significant improvements in performance on some configurations.
+The default
+.I value
+is 1 (on) so you must specify
+.B lazy-count=0
+if you want to disable this feature for older kernels which don't support
+it.
+.RE
+.TP
+.BI \-n " naming_options"
These options specify the version and size parameters for the naming
-(directory) area of the filesystem.
-The valid suboptions are:
-\f3log=\f1\f2value\f1,
-\f3size=\f1\f2value\f1,
-and
-\f3version=\f1\f2value\f1.
-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
-.BR log= ,
-or in bytes with
-.BR size= .
-The default size value for version 2 directories is 4096 bytes (4 KB),
+(directory) area of the filesystem. The valid
+.I naming_options
+are:
+.RS 1.2i
+.TP
+.BI size= value " | log=" value
+The block size is specified either as a
+.I value
+in bytes with
+.BR size= ,
+or as a base two logarithm
+.I value
+.RB "with " log= .
+The block size must be a power of 2 and cannot be less than the
+filesystem block size.
+The default size
+.I value
+for version 2 directories is 4096 bytes (4 KiB),
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
+in which case the default
+.I value
+is the filesystem block size.
+For version 1 directories the block size is the same as the
filesystem block size.
.TP
-\f3\-p\f1 \f2protofile\f1
+.BI version= value
+The naming (directory) version
+.I value
+can be either 2 or 'ci', 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.
+.IP
+The
+.B version=ci
+option enables ASCII only case-insensitive filename lookup and version
+2 directories. Filenames are case-preserving, that is, the names
+are stored in directories using the case they were created with.
+.IP
+Note: Version 1 directories are not supported.
+.TP
+.BI ftype= value
+This feature allows the inode type to be stored in the directory
+structure so that the
+.BR readdir (3)
+and
+.BR getdents (2)
+do not need to look up the inode to determine the inode type.
+
+The
+.I value
+is either 0 or 1, with 1 signifying that filetype information
+will be stored in the directory structure. The default value is 1.
+
+When CRCs are enabled (the default), the ftype functionality is always
+enabled, and cannot be turned off.
+.IP
+.RE
+.TP
+.BI \-p " protofile"
If the optional
-.B \-p
-.I protofile
+.BI \-p " protofile"
argument is given,
-.I mkfs.xfs
+.B mkfs.xfs
uses
.I protofile
-as a prototype file
-and takes its directions from that file.
-The blocks and inodes
-specifiers in the
+as a prototype file and takes its directions from that file.
+The blocks and inodes specifiers in the
.I 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):
+The syntax of the protofile is defined by a number of tokens separated
+by spaces or newlines. Note that the line numbers are not part of the
+syntax but are meant to help you in the following discussion of the file
+contents.
.nf
.sp .8v
.in +5
\f71 /stand/\f1\f2diskboot\f1\f7
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
+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
+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 $\f1
appear at this point for the proto file to be correctly parsed,
but their values are immaterial since they are ignored.
.IP
-Lines 3-11 tell
-.I 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.
-.IP
-The
-.B $
-on line 7 tells
-.I mkfs.xfs
-to end the branch of the filesystem it is on, and continue
-from the next higher directory.
+The lines 3 through 11 specify the files and directories you want to
+include in this filesystem. Line 3 defines the
+root directory. Other directories and
+files that you want in the filesystem
+are indicated by lines 4 through 6 and
+lines 8 through 10. Line 11 contains
+symbolic link syntax.
+.IP
+Notice the dollar sign
+.RB ( $ )
+syntax on line 7. This syntax directs the
+.B mkfs.xfs
+command to terminate the branch of the filesystem it
+is currently on and then continue
+from the directory specified by
+the next line, in this case line 8.
It must be the last character
on a line.
The colon
on lines 13 and 14 end the process, since no additional
specifications follow.
.IP
-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.
-.IP
-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
-.B \-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
-.B u
-or
-.B \-
-to specify setuserID mode or not.
-The third is
-.B g
-or
-.B \-
-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
-.IR chmod (1)).
-.IP
-Two decimal number
-tokens come after the mode; they specify the
-user and group IDs of the owner of the file.
-.IP
-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,
-.I mkfs.xfs
-makes the entries
-.BR . ""
-and
-.B ..
-and then
-reads a list of names and
-(recursively)
-file specifications for the entries
-in the directory.
-As noted above, the scan is terminated with the
-token
-.BR $ .
+File specifications provide the following:
+.IP
+ * file mode
+.br
+ * user ID
+.br
+ * group ID
+.br
+ * the file's beginning contents
+.P
+.IP
+A 6-character string defines the mode for
+a file. The first character of this string
+defines the file type. The character range
+for this first character is
+.B \-bcdpl.
+A file may be a regular file, a block special file,
+a character special file, directory files, named
+pipes (first-in, first out files), and symbolic
+links.
+The second character of the mode string is
+used to specify setuserID mode, in which case
+it is
+.BR u .
+If setuserID mode is not specified, the second character is
+.BR \- .
+The third character of the mode string is
+used to specify the setgroupID mode, in which
+case it is
+.BR g .
+If setgroupID mode is not specified, the third character is
+.BR \- .
+The remaining characters of the mode string are
+a three digit octal number. This octal number
+defines the owner, group, and other read, write,
+and execute permissions for the file, respectively.
+For more information on file permissions, see the
+.BR chmod (1)
+command.
+.IP
+Following the mode character string are two
+decimal number tokens that specify the user and group IDs
+of the file's owner.
+.IP
+In a regular file, the next token specifies the
+pathname from which the contents and size of the
+file are copied.
+In a block or character special file, the next token
+are two decimal numbers that specify the major and minor
+device numbers.
+When a file is a symbolic link, the next token
+specifies the contents of the link.
+
+When the file is a directory, the
+.B mkfs.xfs
+command creates the entries
+.B dot
+(.) and
+.B dot-dot
+(..) and then reads the list of names and file specifications
+in a recursive manner for all of the entries
+in the directory. A scan of the protofile is
+always terminated with the dollar (
+.B $
+) token.
.TP
.B \-q
-Quiet option.
-.IP
-Normally
-.I mkfs.xfs
+Quiet option. Normally
+.B mkfs.xfs
prints the parameters of the filesystem
to be constructed;
the
.B \-q
flag suppresses this.
.TP
-.B \-r
-Real-time section options.
-.IP
+.BI \-r " realtime_section_options"
These options specify the location, size, and other parameters of the
-real-time section of the filesystem.
-The valid suboptions are:
+real-time section of the filesystem. The valid
+.I realtime_section_options
+are:
+.RS 1.2i
+.TP
+.BI rtdev= device
+This is used to specify the
+.I device
+which should contain the real-time section of the filesystem.
+The suboption value is the name of a block device.
+.TP
.BI extsize= value
-and
-\f3size=\f1\f2value\f1.
-.IP
+This is used to specify the size of the blocks in the real-time
+section of the filesystem. This
+.I value
+must be a multiple of the filesystem block size. The minimum allowed
+size is the filesystem block size or 4 KiB (whichever is larger); the
+default size is the stripe width for striped volumes or 64 KiB for
+non-striped volumes; the maximum allowed size is 1 GiB. The real-time
+extent size should be carefully chosen to match the parameters of the
+physical media used.
+.TP
+.BI size= value
+This 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 partition
+or logical volume containing the section.
+.TP
+.BI noalign
+This option disables stripe size detection, enforcing a realtime device with no
+stripe geometry.
+.RE
+.TP
+.BI \-s " sector_size"
+This option specifies the fundamental sector size of the filesystem.
The
-.B 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
-non-striped 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.
+.I sector_size
+is specified either as a value in bytes with
+.BI size= value
+or as a base two logarithm value with
+.BI log= value.
+The default
+.I sector_size
+is 512 bytes. The minimum value for sector size is
+512; the maximum is 32768 (32 KiB). The
+.I sector_size
+must be a power of 2 size and cannot be made larger than the
+filesystem block size.
.IP
-The
-.B 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 partition or logical volume containing the section.
-.TP
-.B \-C
-Disable overlapping partition/volume checks.
-.IP
-By default \f2mkfs.xfs\f1 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.
-.TP
-\f3\-L\f1 \f2label\f1
-Set the filesystem label.
+To specify any options on the command line in units of sectors, this
+option must be specified first so that the sector size is
+applied consistently to all options.
+.TP
+.BI \-L " label"
+Set the filesystem
+.IR label .
XFS filesystem labels can be at most 12 characters long; if
.I label
is longer than 12 characters,
-.I mkfs.xfs
+.B mkfs.xfs
will not proceed with creating the filesystem. Refer to the
-.IR mount (8)
-and
-.IR xfs_admin (8)
+.BR mount "(8) and " xfs_admin (8)
manual entries for additional information.
+.TP
+.B \-N
+Causes the file system parameters to be printed out without really
+creating the file system.
+.TP
+.B \-K
+Do not attempt to discard blocks at mkfs time.
+.TP
+.B \-V
+Prints the version number and exits.
.SH SEE ALSO
-mkfs(8),
-mount(8),
-xfs_admin(8).
+.BR xfs (5),
+.BR mkfs (8),
+.BR mount (8),
+.BR xfs_info (8),
+.BR xfs_admin (8).
.SH BUGS
With a prototype file, it is not possible to specify hard links.
projects / thirdparty / xfsprogs-dev.git / blobdiff