1mke2fs.conf(5)                File Formats Manual               mke2fs.conf(5)
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NAME

6       mke2fs.conf - Configuration file for mke2fs
7

DESCRIPTION

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, ext3, or
11       ext4 filesystems.
12
13       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
20            [section1]
21                 tag1 = value_a
22                 tag1 = value_b
23                 tag2 = value_c
24
25            [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
35       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
39       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
45       Some relations expect a boolean value.  The parser is quite liberal  on
46       recognizing  ``yes'',  '`y'', ``true'', ``t'', ``1'', ``on'', etc. as a
47       boolean true value,  and  ``no'',  ``n'',  ``false'',  ``nil'',  ``0'',
48       ``off'' as a boolean false value.
49
50       The  following  stanzas are used in the mke2fs.conf file.  They will be
51       described in more detail in future sections of this document.
52
53       [defaults]
54              Contains relations which define the default parameters  used  by
55              mke2fs(8).   In  general,  these defaults may be overridden by a
56              definition in the fs_types stanza, or by an command-line  option
57              provided by the user.
58
59       [fs_types]
60              Contains relations which define defaults that should be used for
61              specific filesystem types.  The filesystem type can be specified
62              explicitly using the -T option to mke2fs(8).
63

THE [defaults] STANZA

65       The following relations are defined in the [defaults] stanza.
66
67       base_features
68              This  relation  specifies  the  filesystems  features  which are
69              enabled in newly created filesystems.  It may be  overridden  by
70              the base_features relation found in the filesystem or usage type
71              subsection of the [fs_types] stanza.
72
73       default_features
74              This relation specifies a set of features that should  be  added
75              or removed to the features listed in the base_features relation.
76              It may be overridden by the filesystem-specific default_features
77              in the filesystem or usage type subsection of [fs_types], and by
78              the -O command-line option to mke2fs(8).
79
80       enable_periodic_fsck
81              This boolean  relation  specifies  whether  periodic  filesystem
82              checks  should be enforced at boot time.  If set to true, checks
83              will be forced every 180 days,  or  after  a  random  number  of
84              mounts.   These  values  may  be changed later via the -i and -c
85              command-line options to tune2fs(8).
86
87       force_undo
88              This boolean relation, if set to a value of true, forces  mke2fs
89              to  always  try  to  create  an undo file, even if the undo file
90              might be huge and  it  might  extend  the  time  to  create  the
91              filesystem image because the inode table isn't being initialized
92              lazily.
93
94       fs_type
95              This relation specifies the default filesystem type if the  user
96              does  not  specify  it  via  the  -t option, or if mke2fs is not
97              started using a program name of the form mkfs.fs-type.  If  both
98              the  user  and  the  mke2fs.conf file does not specify a default
99              filesystem type, mke2fs will use a default  filesystem  type  of
100              ext3  if  a  journal was requested via a command-line option, or
101              ext2 if not.
102
103       blocksize
104              This relation specifies the default blocksize if the  user  does
105              not specify a blocksize on the command line, and the filesystem-
106              type specific section of the configuration file does not specify
107              a blocksize.
108
109       hash_alg
110              This  relation specifies the default hash algorithm used for the
111              new filesystems with hashed  b-tree  directories.   Valid  algo‐
112              rithms accepted are: legacy, half_md4, and tea.
113
114       inode_ratio
115              This relation specifies the default inode ratio if the user does
116              not specify one on the command  line,  and  the  filesystem-type
117              specific  section  of  the configuration file does not specify a
118              default inode ratio.
119
120       inode_size
121              This relation specifies the default inode size if the user  does
122              not  specify  one  on  the command line, and the filesystem-type
123              specific section of the configuration file does  not  specify  a
124              default inode size.
125
126       reserved_ratio
127              This  relation  specifies  the  default percentage of filesystem
128              blocks reserved for the super-user, if the user does not specify
129              one  on  the command line, and the filesystem-type specific sec‐
130              tion of the  configuration  file  does  not  specify  a  default
131              reserved ratio. This value can be a floating point number.
132
133       undo_dir
134              This relation specifies the directory where the undo file should
135              be stored.  It can  be  overridden  via  the  E2FSPROGS_UNDO_DIR
136              environment  variable.   If the directory location is set to the
137              value none, mke2fs will not create an undo file.
138

THE [fs_types] STANZA

140       Each tag in the [fs_types] stanza names a filesystem type or usage type
141       which  can  be specified via the -t or -T options to mke2fs(8), respec‐
142       tively.
143
144       The mke2fs program constructs a list of fs_types by  concatenating  the
145       filesystem type (i.e., ext2, ext3, etc.) with the usage type list.  For
146       most configuration options, mke2fs will look for a  subsection  in  the
147       [fs_types]  stanza  corresponding  with  each  entry in the constructed
148       list, with later entries overriding earlier filesystem or usage  types.
149       For example, consider the following mke2fs.conf fragment:
150
151       [defaults]
152            base_features = sparse_super,filetype,resize_inode,dir_index
153            blocksize = 4096
154            inode_size = 256
155            inode_ratio = 16384
156
157       [fs_types]
158            ext3 = {
159                 features = has_journal
160            }
161            ext4 = {
162                 features = extents,flex_bg
163                 inode_size = 256
164            }
165            small = {
166                 blocksize = 1024
167                 inode_ratio = 4096
168            }
169            floppy = {
170                 features = ^resize_inode
171                 blocksize = 1024
172                 inode_size = 128
173            }
174
175       If mke2fs started with a program name of mke2fs.ext4, then the filesys‐
176       tem type of ext4 will be used.  If the filesystem  is  smaller  than  3
177       megabytes,  and  no  usage  type  is  specified, then mke2fs will use a
178       default usage type of floppy.  This results  in  an  fs_types  list  of
179       "ext4,  floppy".    Both  the ext4 subsection and the floppy subsection
180       define an inode_size relation, but  since  the  later  entries  in  the
181       fs_types  list  supersede earlier ones, the configuration parameter for
182       fs_types.floppy.inode_size will be used, so the filesystem   will  have
183       an inode size of 128.
184
185       The  exception  to this resolution is the features tag, which is speci‐
186       fies a set of changes to the features used by the filesystem, and which
187       is  cumulative.  So in the above example, first the configuration rela‐
188       tion defaults.base_features would enable an initial  feature  set  with
189       the   sparse_super,  filetype,  resize_inode,  and  dir_index  features
190       enabled.   Then  configuration  relation  fs_types.ext4.features  would
191       enable  the extents and flex_bg features, and finally the configuration
192       relation fs_types.floppy.features would remove  the  resize_inode  fea‐
193       ture,   resulting  in  a  filesystem  feature  set  consisting  of  the
194       sparse_super, filetype, resize_inode,  dir_index,  extents_and  flex_bg
195       features.
196
197       For  each  filesystem  type,  the  following  tags  may be used in that
198       fs_type's subsection:
199
200       base_features
201              This relation specifies the features which are initially enabled
202              for  this filesystem type.  Only one base_features will be used,
203              so if there are multiple entries in the fs_types list whose sub‐
204              sections  define  the base_features relation, only the last will
205              be used by mke2fs(8).
206
207       features
208              This relation specifies a comma-separated list of features  edit
209              requests  which  modify  the  feature set used by the newly con‐
210              structed filesystem.  The syntax is the same as the -O  command-
211              line  option to mke2fs(8); that is, a feature can be prefixed by
212              a caret ('^') symbol to disable a named feature.   Each  feature
213              relation  specified  in the fs_types list will be applied in the
214              order found in the fs_types list.
215
216       default_features
217              This relation specifies set of features which should be  enabled
218              or  disabled after applying the features listed in the base_fea‐
219              tures and features relations.  It may be overridden  by  the  -O
220              command-line option to mke2fs(8).
221
222       auto_64-bit_support
223              This  relation  is  a  boolean which specifies whether mke2fs(8)
224              should automatically add the 64bit  feature  if  the  number  of
225              blocks  for the file system requires this feature to be enabled.
226              The resize_inode feature is also automatically disabled since it
227              doesn't support 64-bit block numbers.
228
229       default_mntopts
230              This relation specifies the set of mount options which should be
231              enabled by default.  These may be changed at a later  time  with
232              the -o command-line option to tune2fs(8).
233
234       blocksize
235              This  relation  specifies the default blocksize if the user does
236              not specify a blocksize on the command line.
237
238       lazy_itable_init
239              This boolean relation specifies whether the inode  table  should
240              be  lazily  initialized.   It  only has meaning if the uninit_bg
241              feature  is  enabled.   If  lazy_itable_init  is  true  and  the
242              uninit_bg  feature  is  enabled,  the inode table will not fully
243              initialized by mke2fs(8).  This speeds up filesystem initializa‐
244              tion noticeably, but it requires the kernel to finish initializ‐
245              ing the filesystem in the  background  when  the  filesystem  is
246              first mounted.
247
248       inode_ratio
249              This relation specifies the default inode ratio if the user does
250              not specify one on the command line.
251
252       inode_size
253              This relation specifies the default inode size if the user  does
254              not specify one on the command line.
255
256       reserved_ratio
257              This  relation  specifies  the  default percentage of filesystem
258              blocks reserved for the super-user, if the user does not specify
259              one on the command line.
260
261       hash_alg
262              This  relation specifies the default hash algorithm used for the
263              new filesystems with hashed  b-tree  directories.   Valid  algo‐
264              rithms accepted are: legacy, half_md4, and tea.
265
266       flex_bg_size
267              This  relation specifies the number of block groups that will be
268              packed together to create one large virtual block  group  on  an
269              ext4  filesystem.   This improves meta-data locality and perfor‐
270              mance on meta-data heavy workloads.  The number of  groups  must
271              be  a  power  of  2  and  may  only  be specified if the flex_bg
272              filesystem feature is enabled.
273
274       options
275              This relation specifies additional extended options which should
276              be  treated  by mke2fs(8) as if they were prepended to the argu‐
277              ment of the -E option.   This  can  be  used  to  configure  the
278              default  extended  options used by mke2fs(8) on a per-filesystem
279              type basis.
280
281       discard
282              This boolean relation specifies  whether  the  mke2fs(8)  should
283              attempt to discard device prior to filesystem creation.
284
285       cluster_size
286              This relation specifies the default cluster size if the bigalloc
287              file system feature is enabled.  It can be overridden via the -C
288              command line option to mke2fs(8)
289

THE [devices] STANZA

291       Each  tag  in the [devices] stanza names device name so that per-device
292       defaults can be specified.
293
294       fs_type
295              This relation specifies the default parameter for the -t option,
296              if this option isn't specified on the command line.
297
298       usage_types
299              This relation specifies the default parameter for the -T option,
300              if this option isn't specified on the command line.
301

FILES

303       /etc/mke2fs.conf
304              The configuration file for mke2fs(8).
305

SEE ALSO

307       mke2fs(8)
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311E2fsprogs version 1.42.9         December 2013                  mke2fs.conf(5)
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