#Bash 的 mkfs.xfs 命令
mkfs.xfs [OPTION]... DEVICE
功能
构建 XFS 文件系统。
类型
可执行文件（/usr/sbin/mkfs.xfs），属于 xfsprogs。
参数
OPTION选项：-c configuration_file_option- 配置文件选项；有效值为：options=name- 从name文件读取配置
-b block_size_options- 指定文件系统的基本块大小选项；有效值为：size=value- 文件系统块大小为value；单位是字节
-m global_metadata_options- 指定元数据格式选项；有效值为：bigtime=value- 是（1）否（0）启用大时间戳crc=value- 是（1）否（0）启用 CRC 校验finobt=value- 是（1）否（0）在每个分配组中使用单独的空闲 inode b 树索引inobtcount=value- 是（1）否（0）使文件系统记录 inode b 树和空闲 inode b 树所占用的块数uuid=value- 将给定值用作新建文件系统的 UUIDrmapbt=value- 是（1）否（0）允许在每个分配组中创建反向映射 B 树索引reflink=value- 是（1）否（0）允许在每个分配组中使用单独的引用计数 B 树索引
-d data_section_options- 数据段选项；有效值为：agcount=value- 分配组的数量agsize=value- 分配组的大小；单位是字节cowextsize=value- inode 的写时复制扩展大小提示name=value- 指定包含文件系统的特殊文件的名称file[=value]- 名称子选项指定的文件是（1）否（0）为普通文件size=value- 数据段的大小sunit=value,su=value- 指定 RAID 设备或逻辑卷的条带单元swidth=value,sw=value- 指定 RAID 设备或条带化逻辑卷的条带宽度noalign- 禁止对齐rtinherit=value- 是（1）否（0）创建的所有 inode 都将设置实时标志projinherit=value- 创建的所有 inode 都将被分配一个由value提供的项目配额 IDextszinherit=value- 创建的所有 inode 都将应用value扩展大小提示daxinherit=value- 是（1）否（0）创建的所有 inode 都将设置 DAX 标志
-f- 强制覆盖-i inode_options- inode 选项；有效值为：size=value- inode 大小；单位是字节perblock=value- inode 大小；单位是块maxpct=value- 指定文件系统中可分配给 inode 的最大空间百分比align[=value]- 指定 inode 分配是（1）否（0）对齐attr=value- 指定要使用的扩展属性内联分配策略的版本projid32bit[=value]- 是（1）否（0）启用 32 位配额项目标识符sparse[=value]- 启用稀疏 inode 块分配nrext64[=value]- 是（1）否（0）将 inode 数据和属性分支扩展计数器的最大值分别从和 扩展到 和
-l log_section_options- 日志段选项；有效值为：agnum=value- 如果日志是内部日志，则将其分配到此可用性组 (AG) 中internal[=value]- 日志段是（1）否（0）是数据段的一部分logdev=device- 日志段是（1）否（0）与数据部分位于不同的设备上size=value- 日志段的大小version=value- 日志版本sunit=value,su=value- 日志写入的对齐方式lazy-count=value- 超级块中各种持久计数器的日志记录方式
-n naming_options- 文件系统命名（目录）区域选项；有效值为：size=value- 目录块大小；单位是字节version=value- 命名（目录）版本；可以是 2 或ciftype=value- 是（1）否（0）允许将 inode 类型存储在目录结构中
-p protofile_options- protofile 选项；有效值为：[file=]protofile- 指定protofile文件slashes_are_spaces=value- 是（1）否（0）protofile每行第一个标记中的斜杠（“/”）将被转换为空格
-q- 静默执行-r realtime_section_options- 实时段选项；有效值为：rtdev=device- 指定应包含文件系统实时部分的设备extsize=value- 指定文件系统实时段中数据块的大小size=value- 指定实时段的大小noalign- 禁用条带大小检测
-s sector_size_options- 段大小选项；有效值为：size=value- 扇区大小；单位是字节，默认为 512
-L label- 文件系统标签；最多 12 个字符-N- 不实际创建文件系统，而是打印将要执行的操作-K- 不要尝试丢弃数据块-V- 打印版本号
DEVICE- 要操作的设备
#示例
$ sudo mkfs.xfs /dev/sda -f # 将 /dev/sda 格式化为 xfs 文件系统
meta-data=/dev/sda isize=512 agcount=4, agsize=1921030 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=1, rmapbt=1
= reflink=1 bigtime=1 inobtcount=1 nrext64=0
data = bsize=4096 blocks=7684120, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log bsize=4096 blocks=16384, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
#相关命令
#推荐阅读
#手册
mkfs.xfs(8) System Manager's Manual mkfs.xfs(8)
NAME
mkfs.xfs - construct an XFS filesystem
SYNOPSIS
mkfs.xfs [ -b block_size_options ] [ -c config_file_options ] [ -m
global_metadata_options ] [ -d data_section_options ] [ -f ] [ -i in‐
ode_options ] [ -l log_section_options ] [ -n naming_options ] [ -p
protofile_options ] [ -q ] [ -r realtime_section_options ] [ -s sec‐
tor_size_options ] [ -L label ] [ -N ] [ -K ] device
mkfs.xfs -V
DESCRIPTION
mkfs.xfs constructs an XFS filesystem by writing on a special file us‐
ing the values found in the arguments of the command line. It is in‐
voked automatically by mkfs(8) when it is given the -t xfs option.
In its simplest (and most commonly used form), the size of the filesys‐
tem 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:
mkfs.xfs /dev/sda1
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 100MiB log located on the first partition on the
second SCSI disk, use:
mkfs.xfs -l logdev=/dev/sdb1,size=100m /dev/sda1
Each of the option elements in the argument list above can be given as
multiple comma-separated 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=100m
and -l internal -l size=100m are equivalent.
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.
The following lists possible multiplication suffixes:
s - multiply by sector size (default = 512, see -s option be‐
low).
b - multiply by filesystem block size (default = 4K, see -b op‐
tion below).
k - multiply by one kilobyte (1,024 bytes).
m - multiply by one megabyte (1,048,576 bytes).
g - multiply by one gigabyte (1,073,741,824 bytes).
t - multiply by one terabyte (1,099,511,627,776 bytes).
p - multiply by one petabyte (1,024 terabytes).
e - multiply by one exabyte (1,048,576 terabytes).
When specifying parameters in units of sectors or filesystem blocks,
the -s option or the -b option may be used to specify the size of the
sector or block. If the size of the block or sector is not specified,
the default sizes (block: 4KiB, sector: 512B) will be used.
Many feature options allow an optional argument of 0 or 1, to explic‐
itly disable or enable the functionality.
The correctness of the crc32c checksum implementation will be tested
before formatting the filesystem. If the test fails, the format will
abort.
OPTIONS
Options may be specified either on the command line or in a configura‐
tion file. Not all command line options can be specified in configura‐
tion files; only the command line options followed by a [section] label
can be used in a configuration file.
Options that can be used in configuration files are grouped into re‐
lated sections containing multiple options. The command line options
and configuration files use the same option sections and grouping.
Configuration file section names are listed in the command line option
sections below. Option names and values are the same for both command
line and configuration file specification.
Options specified are the combined set of command line parameters and
configuration file parameters. Duplicated options will result in a re‐
specification error, regardless of the location they were specified at.
-c configuration_file_option
This option specifies the files that mkfs configuration will be
obtained from. The valid configuration_file_option is:
options=name
The configuration options will be sourced from the
file specified by the name option string. This op‐
tion can be use either an absolute or relative path
to the configuration file to be read. Sample con‐
figuration files can be found in /usr/share/xf‐
sprogs/mkfs.
-b block_size_options
Section Name: [block]
This option specifies the fundamental block size of the filesys‐
tem. The valid block_size_option is:
size=value
The filesystem block size is specified with a value
in bytes. The default value is 4096 bytes (4 KiB),
the minimum is 512, and the maximum is 65536 (64
KiB).
Although 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.
-m global_metadata_options
Section Name: [metadata]
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 global_metadata_options
are:
bigtime=value
This option enables filesystems that can handle in‐
ode timestamps from December 1901 to July 2486, and
quota timer expirations from January 1970 to July
2486. The value is either 0 to disable the feature,
or 1 to enable large timestamps.
If this feature is not enabled, the filesystem can
only handle timestamps from December 1901 to January
2038, and quota timers from January 1970 to February
2106.
By default, mkfs.xfs will enable this feature. If
the option -m crc=0 is used, the large timestamp
feature is not supported and is disabled.
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 fea‐
ture, or 1 to enable the use of CRCs.
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 archi‐
tecture as some CPUs have hardware acceleration of
this algorithm. Typically the overhead of calculat‐
ing and checking the CRCs is not noticeable in nor‐
mal operation.
By default, mkfs.xfs will enable metadata CRCs.
Formatting a filesystem without CRCs selects the V4
format, which is deprecated and will be removed from
upstream in September 2030. Distributors may choose
to withdraw support for the V4 format earlier than
this date. Several other options, noted below, are
only tunable on V4 formats, and will be removed
along with the V4 format itself.
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.
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 in‐
odes, allowing faster, more consistent inode alloca‐
tion performance as filesystems age.
By default, mkfs.xfs will create free inode btrees
for filesystems created with the (default) -m crc=1
option set. When the option -m crc=0 is used, the
free inode btree feature is not supported and is
disabled.
inobtcount=value
This option causes the filesystem to record the num‐
ber of blocks used by the inode btree and the free
inode btree. This can be used to reduce mount times
when the free inode btree is enabled.
By default, mkfs.xfs will enable this option. This
feature is only available for filesystems created
with the (default) -m finobt=1 option set. When the
option -m finobt=0 is used, the inode btree counter
feature is not supported and is disabled.
uuid=value
Use the given value as the filesystem UUID for the
newly created filesystem. The default is to gener‐
ate a random UUID.
rmapbt=value
This option enables the creation of a reverse-map‐
ping btree index in each allocation group. The
value is either 0 to disable the feature, or 1 to
create the btree.
The reverse mapping btree maps filesystem blocks to
the owner of the filesystem block. Most of the map‐
pings 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.
By default, mkfs.xfs will create reverse mapping
btrees when possible. This feature is only avail‐
able for filesystems created with the (default) -m
crc=1 option set. When the option -m crc=0 is used,
the reverse mapping btree feature is not supported
and is disabled.
reflink=value
This option enables the use of a separate reference
count btree index in each allocation group. The
value is either 0 to disable the feature, or 1 to
create a reference count btree in each allocation
group.
The reference count btree enables the sharing of
physical extents between the data forks of different
files, which is commonly known as "reflink". Unlike
traditional Unix filesystems which assume that every
inode and logical block pair map to a unique physi‐
cal block, a reflink-capable XFS filesystem removes
the uniqueness requirement, allowing up to four bil‐
lion arbitrary inode/logical block pairs to map to a
physical block. If a program tries to write to a
multiply-referenced block in a file, the write will
be redirected to a new block, and that file's logi‐
cal-to-physical mapping will be changed to the new
block ("copy on write"). This feature enables the
creation of per-file snapshots and deduplication.
It is only available for the data forks of regular
files.
By default, mkfs.xfs will create reference count
btrees and therefore will enable the reflink fea‐
ture. This feature is only available for filesys‐
tems created with the (default) -m crc=1 option set.
When the option -m crc=0 is used, the reference
count btree feature is not supported and reflink is
disabled.
-d data_section_options
Section Name: [data]
These options specify the location, size, and other parameters
of the data section of the filesystem. The valid data_sec‐
tion_options are:
agcount=value
This is used to specify the number of allocation
groups. The data section of the filesystem is di‐
vided into allocation groups to improve the perfor‐
mance 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 value al‐
location groups (default value is scaled automati‐
cally based on the underlying device size).
agsize=value
This is an alternative to using the agcount subop‐
tion. The value is the desired size of the alloca‐
tion 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
16MiB, and no more than 1TiB, and may be automati‐
cally adjusted to properly align with the stripe
geometry. The agcount and agsize suboptions are mu‐
tually exclusive.
cowextsize=value
Set the copy-on-write extent size hint on all inodes
created by mkfs.xfs. The value must be provided in
units of filesystem blocks. If the value is zero,
the default value (currently 32 blocks) will be
used. Directories will pass on this hint to newly
created regular files and directories.
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 internal (with a
size, see the -l option below) and there can be no
real-time section.
file[=value]
This is used to specify that the file given by the
name suboption is a regular file. The value is ei‐
ther 0 or 1, with 1 signifying that the file is reg‐
ular. This suboption is used only to make a filesys‐
tem image. If the value is omitted then 1 is as‐
sumed.
size=value
This is used to specify the size of the data sec‐
tion. This suboption is required if -d file[=1] is
given. Otherwise, it is only needed if the filesys‐
tem should occupy less space than the size of the
special file.
The data section must be at least 300MB in size.
sunit=value
This is used to specify the stripe unit for a RAID
device or a logical volume. The value has to be
specified in 512-byte block units. Use the su subop‐
tion 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.
su=value
This is an alternative to using sunit. The su sub‐
option is used to specify the stripe unit for a RAID
device or a striped logical volume. The 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.
swidth=value
This is used to specify the stripe width for a RAID
device or a striped logical volume. The 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.
sw=value
suboption is an alternative to using swidth. The sw
suboption is used to specify the stripe width for a
RAID device or striped logical volume. The value is
expressed as a multiplier of the stripe unit, usu‐
ally the same as the number of stripe members in the
logical volume configuration, or data disks in a
RAID device.
When a filesystem is created on a block device,
mkfs.xfs will automatically query the block device
for appropriate sunit and swidth values if the block
device and the filesystem size would be larger than
1GB.
noalign
This option disables automatic geometry detection
and creates the filesystem without stripe geometry
alignment even if the underlying storage device pro‐
vides this information.
rtinherit=value
If value is set to 1, all inodes created by mkfs.xfs
will be created with the realtime flag set. The de‐
fault is 0. Directories will pass on this flag to
newly created regular files and directories.
projinherit=value
All inodes created by mkfs.xfs will be assigned the
project quota id provided in value. Directories
will pass on the project id to newly created regular
files and directories.
extszinherit=value
All inodes created by mkfs.xfs will have this value
extent size hint applied. The value must be pro‐
vided in units of filesystem blocks. Directories
will pass on this hint to newly created regular
files and directories.
daxinherit=value
If value is set to 1, all inodes created by mkfs.xfs
will be created with the DAX flag set. The default
is 0. Directories will pass on this flag to newly
created regular files and directories. By default,
mkfs.xfs will not enable DAX mode.
-f Force overwrite when an existing filesystem is detected on the
device. By default, mkfs.xfs will not write to the device if it
suspects that there is a filesystem or partition table on the
device already.
-i inode_options
Section Name: [inode]
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: direc‐
tory data, for small directories; attribute data, for small at‐
tribute sets; symbolic link data, for small symbolic links; the
extent list for the file, for files with a small number of ex‐
tents; and the root of a tree describing the location of extents
for the file, for files with a large number of extents.
The valid inode_options are:
size=value | perblock=value
The inode size is specified either as a value in
bytes with size= or as the number fitting in a
filesystem block with perblock=. The minimum (and
default) value is 256 bytes without crc, 512 bytes
with crc enabled. The maximum value is 2048 (2 KiB)
subject to the restriction that the inode size can‐
not exceed one half of the filesystem block size.
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 plat‐
forms) and most applications cannot currently handle
inode numbers greater than 32 significant bits, so
if no inode size is given on the command line,
mkfs.xfs will attempt to choose a size such that in‐
ode numbers will be < 32 bits. If an inode size is
specified, or if a filesystem is sufficiently large,
mkfs.xfs will warn if this will create inode numbers
> 32 significant bits.
maxpct=value
This specifies the maximum percentage of space in
the filesystem that can be allocated to inodes. The
default value is 25% for filesystems under 1TB, 5%
for filesystems under 50TB and 1% for filesystems
over 50TB.
Setting the value to 0 means that essentially all of
the filesystem can become inode blocks (subject to
possible inode32 mount option restrictions, see
xfs(5) for details.)
This value can be modified with xfs_growfs(8).
align[=value]
This 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 in‐
ode alignment when the filesystem needs to be mount‐
able by a version of IRIX that does not have the in‐
ode alignment feature (any release of IRIX before
6.2, and IRIX 6.2 without XFS patches).
This option is only tunable on the deprecated V4
format.
attr=value
This is used to specify the version of extended at‐
tribute inline allocation policy to be used. By de‐
fault, this is 2, which uses an efficient algorithm
for managing the available inline inode space be‐
tween attribute and extent data.
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.
This option is only tunable on the deprecated V4
format.
projid32bit[=value]
This is used to enable 32bit quota project identi‐
fiers. The 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.)
This option is only tunable on the deprecated V4
format.
sparse[=value]
Enable sparse inode chunk allocation. The value is
either 0 or 1, with 1 signifying that sparse alloca‐
tion is enabled. If the value is omitted, 1 is as‐
sumed. Sparse inode allocation is enabled by de‐
fault. This feature is only available for filesys‐
tems formatted with -m crc=1.
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 ex‐
tents are large enough to accommodate a chunk of 64
inodes. Without this feature enabled, inode alloca‐
tions can fail with out of space errors under severe
fragmented free space conditions.
nrext64[=value]
Extend maximum values of inode data and attr fork
extent counters from 2^31 - 1 and 2^15 - 1 to 2^48 -
1 and 2^32 - 1 respectively. If the value is omit‐
ted, 1 is assumed. This feature is disabled by de‐
fault. This feature is only available for filesys‐
tems formatted with -m crc=1.
-l log_section_options
Section Name: [log]
These options specify the location, size, and other parameters
of the log section of the filesystem. The valid log_section_op‐
tions are:
agnum=value
If the log is internal, allocate it in this AG.
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 value is either 0 or
1, with 1 signifying that the log is internal. If
the value is omitted, 1 is assumed.
logdev=device
This is used to specify that the log section should
reside on the device separate from the data section.
The internal=1 and logdev options are mutually ex‐
clusive.
size=value
This is used to specify the size of the log section.
If the log is contained within the data section and
size isn't specified, 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.
Otherwise, the size suboption is only needed if the
log section of the filesystem should occupy less
space than the size of the special file. The value
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.
The log must be at least 64MB in size. The log can‐
not be more than 2GB in size.
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).
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.
This option is only tunable on the deprecated V4
format.
sunit=value
This specifies the alignment to be used for log
writes. The value has to be specified in 512-byte
block units. Use the 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 perfor‐
mance on some configurations such as software RAID5
when the 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 au‐
tomatically selected if the log sunit suboption is
specified.
The su suboption is an alternative to using sunit.
su=value
This is used to specify the log stripe. The value
has to be specified in bytes, (usually using the s
or b suffixes). This value must be a multiple of the
filesystem block size. Version 2 logs are automati‐
cally selected if the log su suboption is specified.
lazy-count=value
This changes the method of logging various persis‐
tent counters in the superblock. Under metadata in‐
tensive workloads, these counters are updated and
logged frequently enough that the superblock updates
become a serialization point in the filesystem. The
value can be either 0 or 1.
With 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 persis‐
tent counter values without needed to keep them in
the superblock. This gives significant improvements
in performance on some configurations. The default
value is 1 (on) so you must specify lazy-count=0 if
you want to disable this feature for older kernels
which don't support it.
This option is only tunable on the deprecated V4
format.
-n naming_options
Section Name: [naming]
These options specify the version and size parameters for the
naming (directory) area of the filesystem. The valid naming_op‐
tions are:
size=value
The directory block size is specified with a value
in bytes. The block size must be a power of 2 and
cannot be less than the filesystem block size. The
default size 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 directo‐
ries the block size is the same as the filesystem
block size.
version=value
The naming (directory) version value can be either 2
or 'ci', defaulting to 2 if unspecified. With ver‐
sion 2 directories, the directory block size can be
any power of 2 size from the filesystem block size
up to 65536.
If the version=ci option is specified, the kernel
will transform certain bytes in filenames before
performing lookup-related operations. The byte se‐
quence given to create a directory entry is per‐
sisted without alterations. The lookup transforma‐
tions are defined as follows:
0x41-0x5a -> 0x61-0x7a
0xc0-0xd6 -> 0xe0-0xf6
0xd8-0xde -> 0xf8-0xfe
This transformation roughly corresponds to case in‐
sensitivity in ISO 8859-1. The transformations are
not compatible with other encodings (e.g. UTF8). Do
not enable this feature unless your entire environ‐
ment has been coerced to ISO 8859-1. This feature
is deprecated and will be removed in September 2030.
Note: Version 1 directories are not supported.
ftype=value
This feature allows the inode type to be stored in
the directory structure so that the readdir(3) and
getdents(2) do not need to look up the inode to de‐
termine the inode type.
The 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 func‐
tionality is always enabled, and cannot be turned
off.
In other words, this option is only tunable on the
deprecated V4 format.
-p protofile_options
Section Name: [proto]
These options specify the protofile parameters for populating
the filesystem. The valid protofile_options are:
[file=]protofile
The file= prefix is not required for this CLI argu‐
ment for legacy reasons. If specified as a config
file directive, the prefix is required.
If the optional 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 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.
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 $
Line 1 is a dummy string. (It was formerly the
bootfilename.) It is present for backward compati‐
bility; 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 im‐
material 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 val‐
ues must appear at this point for the proto file to
be correctly parsed, but their values are immaterial
since they are ignored.
The lines 3 through 11 specify the files and direc‐
tories 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.
Notice the dollar sign ($) syntax on line 7. This
syntax directs the 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 line 12 intro‐
duces a comment; all characters up until the follow‐
ing 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 provide the following:
* file mode
* user ID
* group ID
* the file's beginning contents
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 -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 u. If setuserID mode is not specified,
the second character is -. The third character of
the mode string is used to specify the setgroupID
mode, in which case it is g. If setgroupID mode is
not specified, the third character is -. The re‐
maining 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 chmod(1)
command.
Following the mode character string are two decimal
number tokens that specify the user and group IDs of
the file's owner.
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 mkfs.xfs command
creates the entries dot (.) and 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 termi‐
nated with the dollar ( $ ) token.
slashes_are_spaces=value
If set to 1, slashes ("/") in the first token of
each line of the protofile are converted to spaces.
This enables the creation of a filesystem containing
filenames with spaces. By default, this is set to
0.
-q Quiet option. Normally mkfs.xfs prints the parameters of the
filesystem to be constructed; the -q flag suppresses this.
-r realtime_section_options
Section Name: [realtime]
These options specify the location, size, and other parameters
of the real-time section of the filesystem. The valid real‐
time_section_options are:
rtdev=device
This is used to specify the device which should con‐
tain the real-time section of the filesystem. The
suboption value is the name of a block device.
extsize=value
This is used to specify the size of the blocks in
the real-time section of the filesystem. This 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.
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 vol‐
ume containing the section.
noalign
This option disables stripe size detection, enforc‐
ing a realtime device with no stripe geometry.
-s sector_size_options
Section Name: [sector]
This option specifies the fundamental sector size of the
filesystem. The valid sector_size_option is:
size=value
The sector size is specified with a value in bytes.
The default sector_size is 512 bytes. The minimum
value for sector size is 512; the maximum is 32768
(32 KiB). The sector_size must be a power of 2 size
and cannot be made larger than the filesystem block
size.
-L label
Set the filesystem label. XFS filesystem labels can be at most
12 characters long; if label is longer than 12 characters,
mkfs.xfs will not proceed with creating the filesystem. Refer
to the mount(8) and xfs_admin(8) manual entries for additional
information.
-N Causes the file system parameters to be printed out without re‐
ally creating the file system.
-K Do not attempt to discard blocks at mkfs time.
-V Prints the version number and exits.
Configuration File Format
The configuration file uses a basic INI format to specify sections and
options within a section. Section and option names are case sensitive.
Section names must not contain whitespace. Options are name-value
pairs, ended by the first whitespace in the line. Option names cannot
contain whitespace. Full line comments can be added by starting a line
with a # symbol. If values contain whitespace, then it must be quoted.
The following example configuration file sets the block size to 4096
bytes, turns on reverse mapping btrees and sets the inode size to 2048
bytes.
# Example mkfs.xfs configuration file
[block]
size=4k
[metadata]
rmapbt=1
[inode]
size=2048
SEE ALSO
xfs(5), mkfs(8), mount(8), xfs_info(8), xfs_admin(8).
BUGS
With a prototype file, it is not possible to specify hard links.
mkfs.xfs(8)