1mkfs.xfs(8) System Manager's Manual mkfs.xfs(8)
2
6 mkfs.xfs - construct an XFS filesystem
7
9 mkfs.xfs [ -b block_size ] [ -d data_section_options ] [ -f ] [ -i
10 inode_options ] [ -l log_section_options ] [ -n naming_options ] [ -p
11 protofile ] [ -q ] [ -r realtime_section_options ] [ -s sector_size ] [
12 -L label ] [ -N ] [ -K ] device
13
15 mkfs.xfs constructs an XFS filesystem by writing on a special file
16 using the values found in the arguments of the command line. It is
17 invoked automatically by mkfs(8) when it is given the -t xfs option.
18 In its simplest (and most commonly used form), the size of the filesys‐
20 tem is determined from the disk driver. As an example, to make a
21 filesystem with an internal log on the first partition on the first
22 SCSI disk, use:
23 mkfs.xfs /dev/sda1
25 The metadata log can be placed on another device to reduce the number
27 of disk seeks. To create a filesystem on the first partition on the
28 first SCSI disk with a 10000 block log located on the first partition
29 on the second SCSI disk, use:
30 mkfs.xfs -l logdev=/dev/sdb1,size=10000b /dev/sda1
32 Each of the option elements in the argument list above can be given as
34 multiple comma-separated suboptions if multiple suboptions apply to the
35 same option. Equivalently, each main option can be given multiple
36 times with different suboptions. For example, -l internal,size=10000b
37 and -l internal -l size=10000b are equivalent.
38 In the descriptions below, sizes are given in sectors, bytes, blocks,
40 kilobytes, megabytes, gigabytes, etc. Sizes are treated as hexadecimal
41 if prefixed by 0x or 0X, octal if prefixed by 0, or decimal otherwise.
42 The following lists possible multiplication suffixes:
43 s - multiply by sector size (default = 512, see -s option
44 below).
45 b - multiply by filesystem block size (default = 4K, see -b
46 option below).
47 k - multiply by one kilobyte (1,024 bytes).
48 m - multiply by one megabyte (1,048,576 bytes).
49 g - multiply by one gigabyte (1,073,741,824 bytes).
50 t - multiply by one terabyte (1,099,511,627,776 bytes).
51 p - multiply by one petabyte (1,024 terabytes).
52 e - multiply by one exabyte (1,048,576 terabytes).
53
55 -b block_size_options
56 This option specifies the fundamental block size of the filesys‐
57 tem. The valid block_size_options are: log=value or size=value
58 and only one can be supplied. The block size is specified
59 either as a base two logarithm value with log=, or in bytes with
60 size=. The default value is 4096 bytes (4 KiB), the minimum is
61 512, and the maximum is 65536 (64 KiB). XFS on Linux currently
62 only supports pagesize or smaller blocks.
63 -d data_section_options
65 These options specify the location, size, and other parameters
66 of the data section of the filesystem. The valid data_sec‐
67 tion_options are:
68 agcount=value
70 This is used to specify the number of allocation
71 groups. The data section of the filesystem is
72 divided into allocation groups to improve the per‐
73 formance of XFS. More allocation groups imply that
74 more parallelism can be achieved when allocating
75 blocks and inodes. The minimum allocation group size
76 is 16 MiB; the maximum size is just under 1 TiB.
77 The data section of the filesystem is divided into
78 value allocation groups (default value is scaled
79 automatically based on the underlying device size).
80 agsize=value
82 This is an alternative to using the agcount subop‐
83 tion. The value is the desired size of the alloca‐
84 tion group expressed in bytes (usually using the m
85 or g suffixes). This value must be a multiple of
86 the filesystem block size, and must be at least
87 16MiB, and no more than 1TiB, and may be automati‐
88 cally adjusted to properly align with the stripe
89 geometry. The agcount and agsize suboptions are
90 mutually exclusive.
91 name=value
93 This can be used to specify the name of the special
94 file containing the filesystem. In this case, the
95 log section must be specified as internal (with a
96 size, see the -l option below) and there can be no
97 real-time section.
98 file[=value]
100 This is used to specify that the file given by the
101 name suboption is a regular file. The value is
102 either 0 or 1, with 1 signifying that the file is
103 regular. This suboption is used only to make a
104 filesystem image. If the value is omitted then 1 is
105 assumed.
106 size=value
108 This is used to specify the size of the data sec‐
109 tion. This suboption is required if -d file[=1] is
110 given. Otherwise, it is only needed if the filesys‐
111 tem should occupy less space than the size of the
112 special file.
113 sunit=value
115 This is used to specify the stripe unit for a RAID
116 device or a logical volume. The value has to be
117 specified in 512-byte block units. Use the su subop‐
118 tion to specify the stripe unit size in bytes. This
119 suboption ensures that data allocations will be
120 stripe unit aligned when the current end of file is
121 being extended and the file size is larger than
122 512KiB. Also inode allocations and the internal log
123 will be stripe unit aligned.
124 su=value
126 This is an alternative to using sunit. The su sub‐
127 option is used to specify the stripe unit for a RAID
128 device or a striped logical volume. The value has to
129 be specified in bytes, (usually using the m or g
130 suffixes). This value must be a multiple of the
131 filesystem block size.
132 swidth=value
134 This is used to specify the stripe width for a RAID
135 device or a striped logical volume. The value has to
136 be specified in 512-byte block units. Use the sw
137 suboption to specify the stripe width size in bytes.
138 This suboption is required if -d sunit has been
139 specified and it has to be a multiple of the -d
140 sunit suboption.
141 sw=value
143 suboption is an alternative to using swidth. The sw
144 suboption is used to specify the stripe width for a
145 RAID device or striped logical volume. The value is
146 expressed as a multiplier of the stripe unit, usu‐
147 ally the same as the number of stripe members in the
148 logical volume configuration, or data disks in a
149 RAID device.
150 When a filesystem is created on a logical volume
152 device, mkfs.xfs will automatically query the logi‐
153 cal volume for appropriate sunit and swidth values.
154 noalign
156 This option disables automatic geometry detection
157 and creates the filesystem without stripe geometry
158 alignment even if the underlying storage device pro‐
159 vides this information.
160 -f Force overwrite when an existing filesystem is detected on the
162 device. By default, mkfs.xfs will not write to the device if it
163 suspects that there is a filesystem or partition table on the
164 device already.
165 -i inode_options
167 This option specifies the inode size of the filesystem, and
168 other inode allocation parameters. The XFS inode contains a
169 fixed-size part and a variable-size part. The variable-size
170 part, whose size is affected by this option, can contain: direc‐
171 tory data, for small directories; attribute data, for small
172 attribute sets; symbolic link data, for small symbolic links;
173 the extent list for the file, for files with a small number of
174 extents; and the root of a tree describing the location of
175 extents for the file, for files with a large number of extents.
176 The valid inode_options are:
178 size=value | log=value | perblock=value
180 The inode size is specified either as a value in
181 bytes with size=, a base two logarithm value with
182 log=, or as the number fitting in a filesystem block
183 with perblock=. The mininum (and default) value is
184 256 bytes. The maximum value is 2048 (2 KiB) sub‐
185 ject to the restriction that the inode size cannot
186 exceed one half of the filesystem block size.
187 XFS uses 64-bit inode numbers internally; however,
189 the number of significant bits in an inode number is
190 affected by filesystem geometry. In practice,
191 filesystem size and inode size are the predominant
192 factors. The Linux kernel (on 32 bit hardware plat‐
193 forms) and most applications cannot currently handle
194 inode numbers greater than 32 significant bits, so
195 if no inode size is given on the command line,
196 mkfs.xfs will attempt to choose a size such that
197 inode numbers will be < 32 bits. If an inode size
198 is specified, or if a filesystem is sufficently
199 large, mkfs.xfs will warn if this will create inode
200 numbers > 32 significant bits.
201 maxpct=value
203 This specifies the maximum percentage of space in
204 the filesystem that can be allocated to inodes. The
205 default value is 25% for filesystems under 1TB, 5%
206 for filesystems under 50TB and 1% for filesystems
207 over 50TB.
208 In the default inode allocation mode, inode blocks
210 are chosen such that inode numbers will not exceed
211 32 bits, which restricts the inode blocks to the
212 lower portion of the filesystem. The data block
213 allocator will avoid these low blocks to accommodate
214 the specified maxpct, so a high value may result in
215 a filesystem with nothing but inodes in a signifi‐
216 cant portion of the lower blocks of the filesystem.
217 (This restriction is not present when the filesystem
218 is mounted with the inode64 option on 64-bit plat‐
219 forms).
220 Setting the value to 0 means that essentially all of
222 the filesystem can become inode blocks, subject to
223 inode32 restrictions.
224 This value can be modified with xfs_growfs(8).
226 align[=value]
228 This is used to specify that inode allocation is or
229 is not aligned. The value is either 0 or 1, with 1
230 signifying that inodes are allocated aligned. If
231 the value is omitted, 1 is assumed. The default is
232 that inodes are aligned. Aligned inode access is
233 normally more efficient than unaligned access;
234 alignment must be established at the time the
235 filesystem is created, since inodes are allocated at
236 that time. This option can be used to turn off
237 inode alignment when the filesystem needs to be
238 mountable by a version of IRIX that does not have
239 the inode alignment feature (any release of IRIX
240 before 6.2, and IRIX 6.2 without XFS patches).
241 attr=value
243 This is used to specify the version of extended
244 attribute inline allocation policy to be used. By
245 default, this is 2, which uses an efficient algo‐
246 rithm for managing the available inline inode space
247 between attribute and extent data.
248 The previous version 1, which has fixed regions for
250 attribute and extent data, is kept for backwards
251 compatibility with kernels older than version
252 2.6.16.
253 projid32bit[=value]
255 This is used to enable 32bit quota project identi‐
256 fiers. The value is either 0 or 1, with 1 signifying
257 that 32bit projid are to be enabled. If the value
258 is omitted, 0 is assumed.
259 -l log_section_options
261 These options specify the location, size, and other parameters
262 of the log section of the filesystem. The valid log_sec‐
263 tion_options are:
264 internal[=value]
266 This is used to specify that the log section is a
267 piece of the data section instead of being another
268 device or logical volume. The value is either 0 or
269 1, with 1 signifying that the log is internal. If
270 the value is omitted, 1 is assumed.
271 logdev=device
273 This is used to specify that the log section should
274 reside on the device separate from the data section.
275 The internal=1 and logdev options are mutually
276 exclusive.
277 size=value
279 This is used to specify the size of the log section.
280 If the log is contained within the data section and
282 size isn't specified, mkfs.xfs will try to select a
283 suitable log size depending on the size of the
284 filesystem. The actual logsize depends on the
285 filesystem block size and the directory block size.
286 Otherwise, the size suboption is only needed if the
288 log section of the filesystem should occupy less
289 space than the size of the special file. The value
290 is specified in bytes or blocks, with a b suffix
291 meaning multiplication by the filesystem block size,
292 as described above. The overriding minimum value for
293 size is 512 blocks. With some combinations of
294 filesystem block size, inode size, and directory
295 block size, the minimum log size is larger than 512
296 blocks.
297 version=value
299 This specifies the version of the log. The current
300 default is 2, which allows for larger log buffer
301 sizes, as well as supporting stripe-aligned log
302 writes (see the sunit and su options, below).
303 The previous version 1, which is limited to 32k log
305 buffers and does not support stripe-aligned writes,
306 is kept for backwards compatibility with very old
307 2.4 kernels.
308 sunit=value
310 This specifies the alignment to be used for log
311 writes. The value has to be specified in 512-byte
312 block units. Use the su suboption to specify the log
313 stripe unit size in bytes. Log writes will be
314 aligned on this boundary, and rounded up to this
315 boundary. This gives major improvements in perfor‐
316 mance on some configurations such as software RAID5
317 when the sunit is specified as the filesystem block
318 size. The equivalent byte value must be a multiple
319 of the filesystem block size. Version 2 logs are
320 automatically selected if the log sunit suboption is
321 specified.
322 The su suboption is an alternative to using sunit.
324 su=value
326 This is used to specify the log stripe. The value
327 has to be specified in bytes, (usually using the s
328 or b suffixes). This value must be a multiple of the
329 filesystem block size. Version 2 logs are automati‐
330 cally selected if the log su suboption is specified.
331 lazy-count=value
333 This changes the method of logging various persis‐
334 tent counters in the superblock. Under metadata
335 intensive workloads, these counters are updated and
336 logged frequently enough that the superblock updates
337 become a serialisation point in the filesystem. The
338 value can be either 0 or 1.
339 With lazy-count=1, the superblock is not modified or
341 logged on every change of the persistent counters.
342 Instead, enough information is kept in other parts
343 of the filesystem to be able to maintain the persis‐
344 tent counter values without needed to keep them in
345 the superblock. This gives significant improvements
346 in performance on some configurations. The default
347 value is 1 (on) so you must specify lazy-count=0 if
348 you want to disable this feature for older kernels
349 which don't support it.
350 -n naming_options
352 These options specify the version and size parameters for the
353 naming (directory) area of the filesystem. The valid nam‐
354 ing_options are:
355 size=value | log=value
357 The block size is specified either as a value in
358 bytes with size=, or as a base two logarithm value
359 with log=. The default size value for version 2
360 directories is 4096 bytes (4 KiB), unless the
361 filesystem block size is larger than 4096, in which
362 case the default value is the filesystem block size.
363 For version 1 directories the block size is the same
364 as the filesystem block size.
365 version=value
367 The naming (directory) version value can be either 2
368 or 'ci', defaulting to 2 if unspecified. With ver‐
369 sion 2 directories, the directory block size can be
370 any power of 2 size from the filesystem block size
371 up to 65536.
372 The version=ci option enables ASCII only case-insen‐
374 sitive filename lookup and version 2 directories.
375 Filenames are case-preserving, that is, the names
376 are stored in directories using the case they were
377 created with.
378 Note: Version 1 directories are not supported.
380 -p protofile
382 If the optional -p protofile argument is given, mkfs.xfs uses
383 protofile as a prototype file and takes its directions from that
384 file. The blocks and inodes specifiers in the protofile are
385 provided for backwards compatibility, but are otherwise unused.
386 The syntax of the protofile is defined by a number of tokens
387 separated by spaces or newlines. Note that the line numbers are
388 not part of the syntax but are meant to help you in the follow‐
389 ing discussion of the file contents.
390 1 /stand/diskboot
392 2 4872 110
393 3 d--777 3 1
394 4 usr d--777 3 1
395 5 sh ---755 3 1 /bin/sh
396 6 ken d--755 6 1
397 7 $
398 8 b0 b--644 3 1 0 0
399 9 c0 c--644 3 1 0 0
400 10 fifo p--644 3 1
401 11 slink l--644 3 1 /a/symbolic/link
402 12 : This is a comment line
403 13 $
404 14 $
405 Line 1 is a dummy string. (It was formerly the bootfilename.)
407 It is present for backward compatibility; boot blocks are not
408 used on SGI systems.
409 Note that some string of characters must be present as the first
411 line of the proto file to cause it to be parsed correctly; the
412 value of this string is immaterial since it is ignored.
413 Line 2 contains two numeric values (formerly the numbers of
415 blocks and inodes). These are also merely for backward compati‐
416 bility: two numeric values must appear at this point for the
417 proto file to be correctly parsed, but their values are immate‐
418 rial since they are ignored.
419 The lines 3 through 11 specify the files and directories you
421 want to include in this filesystem. Line 3 defines the root
422 directory. Other directories and files that you want in the
423 filesystem are indicated by lines 4 through 6 and lines 8
424 through 10. Line 11 contains symbolic link syntax.
425 Notice the dollar sign ($) syntax on line 7. This syntax directs
427 the mkfs.xfs command to terminate the branch of the filesystem
428 it is currently on and then continue from the directory speci‐
429 fied by the next line, in this case line 8. It must be the last
430 character on a line. The colon on line 12 introduces a comment;
431 all characters up until the following newline are ignored. Note
432 that this means you cannot have a file in a prototype file whose
433 name contains a colon. The $ on lines 13 and 14 end the
434 process, since no additional specifications follow.
435 File specifications provide the following:
437 * file mode
439 * user ID
440 * group ID
441 * the file's beginning contents
442 A 6-character string defines the mode for a file. The first
444 character of this string defines the file type. The character
445 range for this first character is -bcdpl. A file may be a regu‐
446 lar file, a block special file, a character special file, direc‐
447 tory files, named pipes (first-in, first out files), and sym‐
448 bolic links. The second character of the mode string is used to
449 specify setuserID mode, in which case it is u. If setuserID
450 mode is not specified, the second character is -. The third
451 character of the mode string is used to specify the setgroupID
452 mode, in which case it is g. If setgroupID mode is not speci‐
453 fied, the third character is -. The remaining characters of the
454 mode string are a three digit octal number. This octal number
455 defines the owner, group, and other read, write, and execute
456 permissions for the file, respectively. For more information on
457 file permissions, see the chmod(1) command.
458 Following the mode character string are two decimal number
460 tokens that specify the user and group IDs of the file's owner.
461 In a regular file, the next token specifies the pathname from
463 which the contents and size of the file are copied. In a block
464 or character special file, the next token are two decimal num‐
465 bers that specify the major and minor device numbers. When a
466 file is a symbolic link, the next token specifies the contents
467 of the link.
468 When the file is a directory, the mkfs.xfs command creates the
470 entries dot (.) and dot-dot (..) and then reads the list of
471 names and file specifications in a recursive manner for all of
472 the entries in the directory. A scan of the protofile is always
473 terminated with the dollar ( $ ) token.
474 -q Quiet option. Normally mkfs.xfs prints the parameters of the
476 filesystem to be constructed; the -q flag suppresses this.
477 -r realtime_section_options
479 These options specify the location, size, and other parameters
480 of the real-time section of the filesystem. The valid real‐
481 time_section_options are:
482 rtdev=device
484 This is used to specify the device which should con‐
485 tain the real-time section of the filesystem. The
486 suboption value is the name of a block device.
487 extsize=value
489 This is used to specify the size of the blocks in
490 the real-time section of the filesystem. This value
491 must be a multiple of the filesystem block size. The
492 minimum allowed size is the filesystem block size or
493 4 KiB (whichever is larger); the default size is the
494 stripe width for striped volumes or 64 KiB for non-
495 striped volumes; the maximum allowed size is 1 GiB.
496 The real-time extent size should be carefully chosen
497 to match the parameters of the physical media used.
498 size=value
500 This is used to specify the size of the real-time
501 section. This suboption is only needed if the real-
502 time section of the filesystem should occupy less
503 space than the size of the partition or logical vol‐
504 ume containing the section.
505 noalign
507 This option disables stripe size detection, enforc‐
508 ing a realtime device with no stripe geometry.
509 -s sector_size
511 This option specifies the fundamental sector size of the
512 filesystem. The sector_size is specified either as a value in
513 bytes with size=value or as a base two logarithm value with
514 log=value. The default sector_size is 512 bytes. The minimum
515 value for sector size is 512; the maximum is 32768 (32 KiB). The
516 sector_size must be a power of 2 size and cannot be made larger
517 than the filesystem block size.
518 -L label
520 Set the filesystem label. XFS filesystem labels can be at most
521 12 characters long; if label is longer than 12 characters,
522 mkfs.xfs will not proceed with creating the filesystem. Refer
523 to the mount(8) and xfs_admin(8) manual entries for additional
524 information.
525 -N Causes the file system parameters to be printed out without
527 really creating the file system.
528 -K Do not attempt to discard blocks at mkfs time.
530
532 xfs(5), mkfs(8), mount(8), xfs_info(8), xfs_admin(8).
533
535 With a prototype file, it is not possible to specify hard links.
536 mkfs.xfs(8)