1mke2fs.conf(5) File Formats Manual mke2fs.conf(5)
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6 mke2fs.conf - Configuration file for mke2fs
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9 mke2fs.conf is the configuration file for mke2fs(8). It controls the
10 default parameters used by mke2fs(8) when it is creating ext2 or ext3
11 filesystems.
12 The mke2fs.conf file uses an INI-style format. Stanzas, or top-level
14 sections, are delimited by square braces: [ ]. Within each section,
15 each line defines a relation, which assigns tags to values, or to a
16 subsection, which contains further relations or subsections. An exam‐
17 ple of the INI-style format used by this configuration file follows
18 below:
19 [section1]
21 tag1 = value_a
22 tag1 = value_b
23 tag2 = value_c
24 [section 2]
26 tag3 = {
27 subtag1 = subtag_value_a
28 subtag1 = subtag_value_b
29 subtag2 = subtag_value_c
30 }
31 tag1 = value_d
32 tag2 = value_e
33 }
34 Comments are delimited by a semicolon (';') or a hash ('#') character
36 at the beginning of the comment, and are terminated by the end of line
37 character.
38 Tags and values must be quoted using double quotes if they contain spa‐
40 ces. Within a quoted string, the standard backslash interpretations
41 apply: "\n" (for the newline character), "\t" (for the tab character),
42 "\b" (for the backspace character), and "\\" (for the backslash charac‐
43 ter).
44 The following stanzas are used in the mke2fs.conf file. They will be
46 described in more detail in future sections of this document.
47 [defaults]
49 Contains relations which define the default parameters used by
50 mke2fs(8). In general, these defaults may be overridden by a
51 definition in the fs_types stanza, or by an command-line option
52 provided by the user.
53 [fs_types]
55 Contains relations which define defaults that should be used for
56 specific filesystem types. The filesystem type can be specified
57 explicitly using the -T option to mke2fs(8).
58
60 The following relations are defined in the [defaults] stanza.
61 base_features
63 This relation specifies the filesystems features which are
64 enabled in newly created filesystems. It may be overridden by
65 the base_features relation found in the filesystem or usage type
66 subsection of the [fs_types] stanza.
67 default_features
69 This relation specifies a set of features that should be added
70 or removed to the features listed in the base_features relation.
71 It may be overridden by the filesystem-specific default_features
72 in the filesystem or usage type subsection of [fs_types], and by
73 the -O command-line option to mke2fs(8).
74 enable_periodic_fsck
76 This relation specifies whether periodic filesystem checks
77 should be enforced at boot time. If enabled, checks will be
78 forced every 180 days, or after a random number of mounts.
79 These values may be changed later via the -i and -c command-line
80 options to tune2fs(8).
81 force_undo
83 This relation, if set to a boolean value of true, forces mke2fs
84 to always try to create an undo file, even if the undo file
85 might be huge and it might extend the time to create the
86 filesystem image because the inode table isn't being initialized
87 lazily.
88 fs_type
90 This relation specifies the default filesystem type if the user
91 does not specify it via the -t option, or if mke2fs is not
92 started using a program name of the form mkfs.fs-type. If both
93 the user and the mke2fs.conf file does not specify a default
94 filesystem type, mke2fs will use a default filesystem type of
95 ext3 if a journal was requested via a command-line option, or
96 ext2 if not.
97 blocksize
99 This relation specifies the default blocksize if the user does
100 not specify a blocksize on the command line, and the filesystem-
101 type specific section of the configuration file does not specify
102 a blocksize.
103 hash_alg
105 This relation specifies the default hash algorithm used for the
106 new filesystems with hashed b-tree directories. Valid algo‐
107 rithms accepted are: legacy, half_md4, and tea.
108 inode_ratio
110 This relation specifies the default inode ratio if the user does
111 not specify one on the command line, and the filesystem-type
112 specific section of the configuration file does not specify a
113 default inode ratio.
114 inode_size
116 This relation specifies the default inode size if the user does
117 not specify one on the command line, and the filesystem-type
118 specific section of the configuration file does not specify a
119 default inode size.
120 undo_dir
122 This relation specifies the directory where the undo file should
123 be stored. It can be overridden via the E2FSPROGS_UNDO_DIR
124 environment variable. If the directory location is set to the
125 value none, mke2fs will not create an undo file.
126
128 Each tag in the [fs_types] stanza names a filesystem type or usage type
129 which can be specified via the -t or -T options to mke2fs(8), respec‐
130 tively.
131 The mke2fs program constructs a list of fs_types by concatenating the
133 filesystem type (i.e., ext2, ext3, etc.) with the usage type list. For
134 most configuration options, mke2fs will look for a subsection in the
135 [fs_types] stanza corresponding with each entry in the constructed
136 list, with later entries overriding earlier filesystem or usage types.
137 For example, consider the following mke2fs.conf fragment:
138 [defaults]
140 base_features = sparse_super,filetype,resize_inode,dir_index
141 blocksize = 4096
142 inode_size = 256
143 inode_ratio = 16384
144 [fs_types]
146 ext3 = {
147 features = has_journal
148 }
149 ext4 = {
150 features = extents,flex_bg
151 inode_size = 256
152 }
153 small = {
154 blocksize = 1024
155 inode_ratio = 4096
156 }
157 floppy = {
158 features = ^resize_inode
159 blocksize = 1024
160 inode_size = 128
161 }
162 If mke2fs started with a program name of mke2fs.ext4, then the filesys‐
164 tem type of ext4 will be used. If the filesystem is smaller than 3
165 megabytes, and no usage type is specified, then mke2fs will use a
166 default usage type of floppy. This results in an fs_types list of
167 "ext4, floppy". Both the ext4 subsection and the floppy subsection
168 define an inode_size relation, but since the later entries in the
169 fs_types list supersede earlier ones, the configuration parameter for
170 fs_types.floppy.inode_size will be used, so the filesystem will have
171 an inode size of 128.
172 The exception to this resolution is the features tag, which is speci‐
174 fies a set of changes to the features used by the filesystem, and which
175 is cumulative. So in the above example, first the configuration rela‐
176 tion defaults.base_features would enable an initial feature set with
177 the sparse_super, filetype, resize_inode, and dir_index features
178 enabled. Then configuration relation fs_types.ext4.features would
179 enable the extents and flex_bg features, and finally the configuration
180 relation fs_types.floppy.features would remove the resize_inode fea‐
181 ture, resulting in a filesystem feature set consisting of the
182 sparse_super, filetype, resize_inode, dir_index, extents_and flex_bg
183 features.
184 For each filesystem type, the following tags may be used in that
186 fs_type's subsection:
187 base_features
189 This relation specifies the features which are initially enabled
190 for this filesystem type. Only one base_features will be used,
191 so if there are multiple entries in the fs_types list whose sub‐
192 sections define the base_features relation, only the last will
193 be used by mke2fs(8).
194 features
196 This relation specifies a comma-separated list of features edit
197 requests which modify the feature set used by the newly con‐
198 structed filesystem. The syntax is the same as the -O command-
199 line option to mke2fs(8); that is, a feature can be prefixed by
200 a caret ('^') symbol to disable a named feature. Each feature
201 relation specified in the fs_types list will be applied in the
202 order found in the fs_types list.
203 default_features
205 This relation specifies set of features which should be enabled
206 or disabled after applying the features listed in the base_fea‐
207 tures and features relations. It may be overridden by the -O
208 command-line option to mke2fs(8).
209 blocksize
211 This relation specifies the default blocksize if the user does
212 not specify a blocksize on the command line.
213 lazy_itable_init
215 This relation is a boolean which specifies whether the inode ta‐
216 ble should be lazily initialized. It only has meaning if the
217 uninit_bg feature is enabled. If lazy_itable_init is true and
218 the uninit_bg feature is enabled, the inode table will not
219 fully initialized by mke2fs(8). This speeds up filesystem ini‐
220 tialization noticeably, but it requires the kernel to finish
221 initializing the filesystem in the background when the filesys‐
222 tem is first mounted.
223 inode_ratio
225 This relation specifies the default inode ratio if the user does
226 not specify one on the command line.
227 inode_size
229 This relation specifies the default inode size if the user does
230 not specify one on the command line.
231 hash_alg
233 This relation specifies the default hash algorithm used for the
234 new filesystems with hashed b-tree directories. Valid algo‐
235 rithms accepted are: legacy, half_md4, and tea.
236 flex_bg_size
238 This relation specifies the number of block groups that will be
239 packed together to create one large virtual block group on an
240 ext4 filesystem. This improves meta-data locality and perfor‐
241 mance on meta-data heavy workloads. The number of groups must
242 be a power of 2 and may only be specified if the flex_bg
243 filesystem feature is enabled. options This relation specifies
244 additional extended options which should be treated by mke2fs(8)
245 as if they were prepended to the argument of the -E option.
246 This can be used to configure the default extended options used
247 by mke2fs(8) on a per-filesystem type basis.
248 discard
250 This relation is a boolean which specifies whether the mke2fs(8)
251 should attempt to discard device prior to filesystem creation.
252
254 /etc/mke2fs.conf
255 The configuration file for mke2fs(8).
256
258 mke2fs(8)
259E2fsprogs version 1.41.12 May 2010 mke2fs.conf(5)