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NAME | DESCRIPTION | THE [options] STANZA | THE [defaults] STANZA | THE [fs_types] STANZA | THE [devices] STANZA | FILES | SEE ALSO | COLOPHON |
mke2fs.conf(5) File Formats Manual mke2fs.conf(5)
mke2fs.conf - Configuration file for mke2fs
mke2fs.conf is the configuration file for mke2fs(8). It controls the
default parameters used by mke2fs(8) when it is creating ext2, ext3,
or ext4 filesystems.
The mke2fs.conf file uses an INI-style format. Stanzas, or top-level
sections, are delimited by square braces: [ ]. Within each section,
each line defines a relation, which assigns tags to values, or to a
subsection, which contains further relations or subsections. An
example of the INI-style format used by this configuration file
follows below:
[section1]
tag1 = value_a
tag1 = value_b
tag2 = value_c
[section 2]
tag3 = {
subtag1 = subtag_value_a
subtag1 = subtag_value_b
subtag2 = subtag_value_c
}
tag1 = value_d
tag2 = value_e
}
Comments are delimited by a semicolon (';') or a hash ('#') character
at the beginning of the comment, and are terminated by the end of
line character.
Tags and values must be quoted using double quotes if they contain
spaces. Within a quoted string, the standard backslash
interpretations apply: "\n" (for the newline character), "\t" (for
the tab character), "\b" (for the backspace character), and "\\" (for
the backslash character).
Some relations expect a boolean value. The parser is quite liberal
on recognizing ``yes'', '`y'', ``true'', ``t'', ``1'', ``on'', etc.
as a boolean true value, and ``no'', ``n'', ``false'', ``nil'',
``0'', ``off'' as a boolean false value.
The following stanzas are used in the mke2fs.conf file. They will be
described in more detail in future sections of this document.
[options]
Contains relations which influence how mke2fs behaves.
[defaults]
Contains relations which define the default parameters used by
mke2fs(8). In general, these defaults may be overridden by a
definition in the fs_types stanza, or by an command-line
option provided by the user.
[fs_types]
Contains relations which define defaults that should be used
for specific file system and usage types. The file system
type and usage type can be specified explicitly using the
-tand-T options to mke2fs(8), respectively.
The following relations are defined in the [options] stanza.
proceed_delay
If this relation is set to a positive integer, then if mke2fs
will proceed after waiting proceed_delay seconds, after asking
the user for permission to proceed, even if the user has not
answered the question. Defaults to 0, which means to wait
until the user answers the question one way or another.
The following relations are defined in the [defaults] stanza.
base_features
This relation specifies the filesystems features which are
enabled in newly created filesystems. It may be overridden by
the base_features relation found in the filesystem or usage
type subsection of the [fs_types] stanza.
default_features
This relation specifies a set of features that should be added
or removed to the features listed in the base_features
relation. It may be overridden by the filesystem-specific
default_features in the filesystem or usage type subsection of
[fs_types], and by the -O command-line option to mke2fs(8).
enable_periodic_fsck
This boolean relation specifies whether periodic filesystem
checks should be enforced at boot time. If set to true,
checks will be forced every 180 days, or after a random number
of mounts. These values may be changed later via the -i and
-c command-line options to tune2fs(8).
force_undo
This boolean relation, if set to a value of true, forces
mke2fs to always try to create an undo file, even if the undo
file might be huge and it might extend the time to create the
filesystem image because the inode table isn't being
initialized lazily.
fs_type
This relation specifies the default filesystem type if the
user does not specify it via the -t option, or if mke2fs is
not started using a program name of the form mkfs.fs-type. If
both the user and the mke2fs.conf file do not specify a
default filesystem type, mke2fs will use a default filesystem
type of ext3 if a journal was requested via a command-line
option, or ext2 if not.
undo_dir
This relation specifies the directory where the undo file
should be stored. It can be overridden via the
E2FSPROGS_UNDO_DIR environment variable. If the directory
location is set to the value none, mke2fs will not create an
undo file.
In addition, any tags that can be specified in a per-file system tags
subsection as defined below (e.g., blocksize, hash_alg, inode_ratio,
inode_size, reserved_ratio, etc.) can also be specified in the
defaults stanza to specify the default value to be used if the user
does not specify one on the command line, and the filesystem-type
specific section of the configuration file does not specify a default
value.
Each tag in the [fs_types] stanza names a filesystem type or usage
type which can be specified via the -t or -T options to mke2fs(8),
respectively.
The mke2fs program constructs a list of fs_types by concatenating the
filesystem type (i.e., ext2, ext3, etc.) with the usage type list.
For most configuration options, mke2fs will look for a subsection in
the [fs_types] stanza corresponding with each entry in the
constructed list, with later entries overriding earlier filesystem or
usage types. For example, consider the following mke2fs.conf
fragment:
[defaults]
base_features = sparse_super,filetype,resize_inode,dir_index
blocksize = 4096
inode_size = 256
inode_ratio = 16384
[fs_types]
ext3 = {
features = has_journal
}
ext4 = {
features = extents,flex_bg
inode_size = 256
}
small = {
blocksize = 1024
inode_ratio = 4096
}
floppy = {
features = ^resize_inode
blocksize = 1024
inode_size = 128
}
If mke2fs started with a program name of mke2fs.ext4, then the
filesystem type of ext4 will be used. If the filesystem is smaller
than 3 megabytes, and no usage type is specified, then mke2fs will
use a default usage type of floppy. This results in an fs_types list
of "ext4, floppy". Both the ext4 subsection and the floppy
subsection define an inode_size relation, but since the later entries
in the fs_types list supersede earlier ones, the configuration
parameter for fs_types.floppy.inode_size will be used, so the
filesystem will have an inode size of 128.
The exception to this resolution is the features tag, which specifies
a set of changes to the features used by the filesystem, and which is
cumulative. So in the above example, first the configuration
relation defaults.base_features would enable an initial feature set
with the sparse_super, filetype, resize_inode, and dir_index features
enabled. Then configuration relation fs_types.ext4.features would
enable the extents and flex_bg features, and finally the
configuration relation fs_types.floppy.features would remove the
resize_inode feature, resulting in a filesystem feature set
consisting of the sparse_super, filetype, dir_index, extents_and
flex_bg features.
For each filesystem type, the following tags may be used in that
fs_type's subsection. These tags may also be used in the default
section:
base_features
This relation specifies the features which are initially
enabled for this filesystem type. Only one base_features will
be used, so if there are multiple entries in the fs_types list
whose subsections define the base_features relation, only the
last will be used by mke2fs(8).
errors Change the behavior of the kernel code when errors are
detected. In all cases, a filesystem error will cause
e2fsck(8) to check the filesystem on the next boot. errors
can be one of the following:
continue Continue normal execution.
remount-ro Remount filesystem read-only.
panic Cause a kernel panic.
features
This relation specifies a comma-separated list of features
edit requests which modify the feature set used by the newly
constructed filesystem. The syntax is the same as the -O
command-line option to mke2fs(8); that is, a feature can be
prefixed by a caret ('^') symbol to disable a named feature.
Each feature relation specified in the fs_types list will be
applied in the order found in the fs_types list.
default_features
This relation specifies set of features which should be
enabled or disabled after applying the features listed in the
base_features and features relations. It may be overridden by
the -O command-line option to mke2fs(8).
auto_64-bit_support
This relation is a boolean which specifies whether mke2fs(8)
should automatically add the 64bit feature if the number of
blocks for the file system requires this feature to be
enabled. The resize_inode feature is also automatically
disabled since it doesn't support 64-bit block numbers.
default_mntopts
This relation specifies the set of mount options which should
be enabled by default. These may be changed at a later time
with the -o command-line option to tune2fs(8).
blocksize
This relation specifies the default blocksize if the user does
not specify a blocksize on the command line.
lazy_itable_init
This boolean relation specifies whether the inode table should
be lazily initialized. It only has meaning if the uninit_bg
feature is enabled. If lazy_itable_init is true and the
uninit_bg feature is enabled, the inode table will not be
fully initialized by mke2fs(8). This speeds up filesystem
initialization noticeably, but it requires the kernel to
finish initializing the filesystem in the background when the
filesystem is first mounted.
journal_location
This relation specifies the location of the journal.
num_backup_sb
This relation indicates whether file systems with the
sparse_super2 feature enabled should be created with 0, 1, or
2 backup superblocks.
packed_meta_blocks
This boolean relation specifes whether the allocation bitmaps,
inode table, and journal should be located at the beginning of
the file system.
inode_ratio
This relation specifies the default inode ratio if the user
does not specify one on the command line.
inode_size
This relation specifies the default inode size if the user
does not specify one on the command line.
reserved_ratio
This relation specifies the default percentage of filesystem
blocks reserved for the super-user, if the user does not
specify one on the command line.
hash_alg
This relation specifies the default hash algorithm used for
the new filesystems with hashed b-tree directories. Valid
algorithms accepted are: legacy, half_md4, and tea.
flex_bg_size
This relation specifies the number of block groups that will
be packed together to create one large virtual block group on
an ext4 filesystem. This improves meta-data locality and
performance on meta-data heavy workloads. The number of
groups must be a power of 2 and may only be specified if the
flex_bg filesystem feature is enabled.
options
This relation specifies additional extended options which
should be treated by mke2fs(8) as if they were prepended to
the argument of the -E option. This can be used to configure
the default extended options used by mke2fs(8) on a per-
filesystem type basis.
discard
This boolean relation specifies whether the mke2fs(8) should
attempt to discard device prior to filesystem creation.
cluster_size
This relation specifies the default cluster size if the
bigalloc file system feature is enabled. It can be overridden
via the -C command line option to mke2fs(8)
make_hugefiles
This boolean relation enables the creation of pre-allocated
files as part of formatting the file system. The extent tree
blocks for these pre-allocated files will be placed near the
beginning of the file system, so that if all of the other
metadata blocks are also configured to be placed near the
beginning of the file system (by disabling the backup
superblocks, using the packed_meta_blocks option, etc.), the
data blocks of the pre-allocated files will be contiguous.
hugefiles_uid
This relation controls the user ownership for all of the files
and directories created by the make_hugefiles feature.
hugefiles_gid
This relation controls the group ownership for all of the
files and directories created by the make_hugefiles feature.
hugefiles_umask
This relation specifies the umask used when creating the files
and directories by the make_hugefiles feature.
num_hugefiles
This relation specifies the number of huge files to be
created. If this relation is not specified, or is set to
zero, and the hugefiles_size relation is non-zero, then
make_hugefiles will create as many huge files as can fit to
fill the entire file system.
hugefiles_slack
This relation specifies how much space should be reserved for
other files.
hugefiles_size
This relation specifies the size of the huge files. If this
relation is not specified, the default is to fill the entire
file system.
hugefiles_align
This relation specifies the alignment for the start block of
the huge files. It also forces the size of huge files to be a
multiple of the requested alignment. If this relation is not
specified, no alignment requirement will be imposed on the
huge files.
hugefiles_align_disk
This relations specifies whether the alignment should be
relative to the beginning of the hard drive (assuming that the
starting offset of the partition is available to mke2fs). The
default value is false, which will cause hugefile alignment to
be relative to the beginning of the file system.
hugefiles_name
This relation specifies the base file name for the huge files.
hugefiles_digits
This relation specifies the (zero-padded) width of the field
for the huge file number.
zero_hugefiles
This boolean relation specifies whether or not zero blocks
will be written to the hugefiles while mke2fs(8) is creating
them. By default, zero blocks will be written to the huge
files to avoid stale data from being made available to
potentially untrusted user programs, unless the device
supports a discard/trim operation which will take care of
zeroing the device blocks. By setting zero_hugefiles to
false, this step will always be skipped, which can be useful
if it is known that the disk has been previously erased, or if
the user programs that will have access to the huge files are
trusted to not reveal stale data.
Each tag in the [devices] stanza names device name so that per-device
defaults can be specified.
fs_type
This relation specifies the default parameter for the -t
option, if this option isn't specified on the command line.
usage_types
This relation specifies the default parameter for the -T
option, if this option isn't specified on the command line.
/etc/mke2fs.conf
The configuration file for mke2fs(8).
mke2fs(8)
This page is part of the e2fsprogs (utilities for ext2/3/4
filesystems) project. Information about the project can be found at
⟨http://e2fsprogs.sourceforge.net/⟩. It is not known how to report
bugs for this man page; if you know, please send a mail to
man-pages@man7.org. This page was obtained from the project's
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⟨git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git⟩ on 2017-07-05.
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E2fsprogs version 1.43.5-WIP February 2017 mke2fs.conf(5)
Pages that refer to this page: ext4(5), mke2fs(8)