1mkfs.xfs(8) System Manager's Manual mkfs.xfs(8)
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6 mkfs.xfs - construct an XFS filesystem
7
9 mkfs.xfs [ -b block_size_options ] [ -c config_file_options ] [ -m
10 global_metadata_options ] [ -d data_section_options ] [ -f ] [ -i in‐
11 ode_options ] [ -l log_section_options ] [ -n naming_options ] [ -p
12 protofile ] [ -q ] [ -r realtime_section_options ] [ -s sector_size_op‐
13 tions ] [ -L label ] [ -N ] [ -K ] device
14 mkfs.xfs -V
15
17 mkfs.xfs constructs an XFS filesystem by writing on a special file us‐
18 ing the values found in the arguments of the command line. It is in‐
19 voked automatically by mkfs(8) when it is given the -t xfs option.
20 In its simplest (and most commonly used form), the size of the filesys‐
22 tem is determined from the disk driver. As an example, to make a
23 filesystem with an internal log on the first partition on the first
24 SCSI disk, use:
25 mkfs.xfs /dev/sda1
27 The metadata log can be placed on another device to reduce the number
29 of disk seeks. To create a filesystem on the first partition on the
30 first SCSI disk with a 100MiB log located on the first partition on the
31 second SCSI disk, use:
32 mkfs.xfs -l logdev=/dev/sdb1,size=100m /dev/sda1
34 Each of the option elements in the argument list above can be given as
36 multiple comma-separated suboptions if multiple suboptions apply to the
37 same option. Equivalently, each main option can be given multiple
38 times with different suboptions. For example, -l internal,size=100m
39 and -l internal -l size=100m are equivalent.
40 In the descriptions below, sizes are given in sectors, bytes, blocks,
42 kilobytes, megabytes, gigabytes, etc. Sizes are treated as hexadecimal
43 if prefixed by 0x or 0X, octal if prefixed by 0, or decimal otherwise.
44 The following lists possible multiplication suffixes:
45 s - multiply by sector size (default = 512, see -s option be‐
46 low).
47 b - multiply by filesystem block size (default = 4K, see -b op‐
48 tion below).
49 k - multiply by one kilobyte (1,024 bytes).
50 m - multiply by one megabyte (1,048,576 bytes).
51 g - multiply by one gigabyte (1,073,741,824 bytes).
52 t - multiply by one terabyte (1,099,511,627,776 bytes).
53 p - multiply by one petabyte (1,024 terabytes).
54 e - multiply by one exabyte (1,048,576 terabytes).
55 When specifying parameters in units of sectors or filesystem blocks,
57 the -s option or the -b option may be used to specify the size of the
58 sector or block. If the size of the block or sector is not specified,
59 the default sizes (block: 4KiB, sector: 512B) will be used.
60 Many feature options allow an optional argument of 0 or 1, to explic‐
62 itly disable or enable the functionality.
63 The correctness of the crc32c checksum implementation will be tested
65 before formatting the filesystem. If the test fails, the format will
66 abort.
67
69 Options may be specified either on the command line or in a configura‐
70 tion file. Not all command line options can be specified in configura‐
71 tion files; only the command line options followed by a [section] label
72 can be used in a configuration file.
73 Options that can be used in configuration files are grouped into re‐
75 lated sections containing multiple options. The command line options
76 and configuration files use the same option sections and grouping.
77 Configuration file section names are listed in the command line option
78 sections below. Option names and values are the same for both command
79 line and configuration file specification.
80 Options specified are the combined set of command line parameters and
82 configuration file parameters. Duplicated options will result in a re‐
83 specification error, regardless of the location they were specified at.
84 -c configuration_file_option
86 This option specifies the files that mkfs configuration will be
87 obtained from. The valid configuration_file_option is:
88 options=name
90 The configuration options will be sourced from the
91 file specified by the name option string. This op‐
92 tion can be use either an absolute or relative path
93 to the configuration file to be read. Sample con‐
94 figuration files can be found in /usr/share/xf‐
95 sprogs/mkfs.
96 -b block_size_options
98 Section Name: [block]
99 This option specifies the fundamental block size of the filesys‐
100 tem. The valid block_size_option is:
101 size=value
103 The filesystem block size is specified with a value
104 in bytes. The default value is 4096 bytes (4 KiB),
105 the minimum is 512, and the maximum is 65536 (64
106 KiB).
107 Although mkfs.xfs will accept any of these values
109 and create a valid filesystem, XFS on Linux can only
110 mount filesystems with pagesize or smaller blocks.
111 -m global_metadata_options
113 Section Name: [metadata]
114 These options specify metadata format options that either apply
115 to the entire filesystem or aren't easily characterised by a
116 specific functionality group. The valid global_metadata_options
117 are:
118 bigtime=value
120 This option enables filesystems that can handle in‐
121 ode timestamps from December 1901 to July 2486, and
122 quota timer expirations from January 1970 to July
123 2486. The value is either 0 to disable the feature,
124 or 1 to enable large timestamps.
125 If this feature is not enabled, the filesystem can
127 only handle timestamps from December 1901 to January
128 2038, and quota timers from January 1970 to February
129 2106.
130 By default, mkfs.xfs will enable this feature. If
132 the option -m crc=0 is used, the large timestamp
133 feature is not supported and is disabled.
134 crc=value
136 This is used to create a filesystem which maintains
137 and checks CRC information in all metadata objects
138 on disk. The value is either 0 to disable the fea‐
139 ture, or 1 to enable the use of CRCs.
140 CRCs enable enhanced error detection due to hardware
142 issues, whilst the format changes also improves
143 crash recovery algorithms and the ability of various
144 tools to validate and repair metadata corruptions
145 when they are found. The CRC algorithm used is
146 CRC32c, so the overhead is dependent on CPU archi‐
147 tecture as some CPUs have hardware acceleration of
148 this algorithm. Typically the overhead of calculat‐
149 ing and checking the CRCs is not noticeable in nor‐
150 mal operation.
151 By default, mkfs.xfs will enable metadata CRCs.
153 Formatting a filesystem without CRCs selects the V4
155 format, which is deprecated and will be removed from
156 upstream in September 2030. Distributors may choose
157 to withdraw support for the V4 format earlier than
158 this date. Several other options, noted below, are
159 only tunable on V4 formats, and will be removed
160 along with the V4 format itself.
161 finobt=value
163 This option enables the use of a separate free inode
164 btree index in each allocation group. The value is
165 either 0 to disable the feature, or 1 to create a
166 free inode btree in each allocation group.
167 The free inode btree mirrors the existing allocated
169 inode btree index which indexes both used and free
170 inodes. The free inode btree does not index used in‐
171 odes, allowing faster, more consistent inode alloca‐
172 tion performance as filesystems age.
173 By default, mkfs.xfs will create free inode btrees
175 for filesystems created with the (default) -m crc=1
176 option set. When the option -m crc=0 is used, the
177 free inode btree feature is not supported and is
178 disabled.
179 inobtcount=value
181 This option causes the filesystem to record the num‐
182 ber of blocks used by the inode btree and the free
183 inode btree. This can be used to reduce mount times
184 when the free inode btree is enabled.
185 By default, mkfs.xfs will enable this option. This
187 feature is only available for filesystems created
188 with the (default) -m finobt=1 option set. When the
189 option -m finobt=0 is used, the inode btree counter
190 feature is not supported and is disabled.
191 uuid=value
193 Use the given value as the filesystem UUID for the
194 newly created filesystem. The default is to gener‐
195 ate a random UUID.
196 rmapbt=value
198 This option enables the creation of a reverse-map‐
199 ping btree index in each allocation group. The
200 value is either 0 to disable the feature, or 1 to
201 create the btree.
202 The reverse mapping btree maps filesystem blocks to
204 the owner of the filesystem block. Most of the map‐
205 pings will be to an inode number and an offset,
206 though there will also be mappings to filesystem
207 metadata. This secondary metadata can be used to
208 validate the primary metadata or to pinpoint exactly
209 which data has been lost when a disk error occurs.
210 By default, mkfs.xfs will not create reverse mapping
212 btrees. This feature is only available for filesys‐
213 tems created with the (default) -m crc=1 option set.
214 When the option -m crc=0 is used, the reverse map‐
215 ping btree feature is not supported and is disabled.
216 reflink=value
218 This option enables the use of a separate reference
219 count btree index in each allocation group. The
220 value is either 0 to disable the feature, or 1 to
221 create a reference count btree in each allocation
222 group.
223 The reference count btree enables the sharing of
225 physical extents between the data forks of different
226 files, which is commonly known as "reflink". Unlike
227 traditional Unix filesystems which assume that every
228 inode and logical block pair map to a unique physi‐
229 cal block, a reflink-capable XFS filesystem removes
230 the uniqueness requirement, allowing up to four bil‐
231 lion arbitrary inode/logical block pairs to map to a
232 physical block. If a program tries to write to a
233 multiply-referenced block in a file, the write will
234 be redirected to a new block, and that file's logi‐
235 cal-to-physical mapping will be changed to the new
236 block ("copy on write"). This feature enables the
237 creation of per-file snapshots and deduplication.
238 It is only available for the data forks of regular
239 files.
240 By default, mkfs.xfs will create reference count
242 btrees and therefore will enable the reflink fea‐
243 ture. This feature is only available for filesys‐
244 tems created with the (default) -m crc=1 option set.
245 When the option -m crc=0 is used, the reference
246 count btree feature is not supported and reflink is
247 disabled.
248 Note: the filesystem DAX mount option ( -o dax ) is
250 incompatible with reflink-enabled XFS filesystems.
251 To use filesystem DAX with XFS, specify the -m re‐
252 flink=0 option to mkfs.xfs to disable the reflink
253 feature.
254 -d data_section_options
256 Section Name: [data]
257 These options specify the location, size, and other parameters
258 of the data section of the filesystem. The valid data_sec‐
259 tion_options are:
260 agcount=value
262 This is used to specify the number of allocation
263 groups. The data section of the filesystem is di‐
264 vided into allocation groups to improve the perfor‐
265 mance of XFS. More allocation groups imply that more
266 parallelism can be achieved when allocating blocks
267 and inodes. The minimum allocation group size is 16
268 MiB; the maximum size is just under 1 TiB. The data
269 section of the filesystem is divided into value al‐
270 location groups (default value is scaled automati‐
271 cally based on the underlying device size).
272 agsize=value
274 This is an alternative to using the agcount subop‐
275 tion. The value is the desired size of the alloca‐
276 tion group expressed in bytes (usually using the m
277 or g suffixes). This value must be a multiple of
278 the filesystem block size, and must be at least
279 16MiB, and no more than 1TiB, and may be automati‐
280 cally adjusted to properly align with the stripe ge‐
281 ometry. The agcount and agsize suboptions are mutu‐
282 ally exclusive.
283 cowextsize=value
285 Set the copy-on-write extent size hint on all inodes
286 created by mkfs.xfs. The value must be provided in
287 units of filesystem blocks. If the value is zero,
288 the default value (currently 32 blocks) will be
289 used. Directories will pass on this hint to newly
290 created regular files and directories.
291 name=value
293 This can be used to specify the name of the special
294 file containing the filesystem. In this case, the
295 log section must be specified as internal (with a
296 size, see the -l option below) and there can be no
297 real-time section.
298 file[=value]
300 This is used to specify that the file given by the
301 name suboption is a regular file. The value is ei‐
302 ther 0 or 1, with 1 signifying that the file is reg‐
303 ular. This suboption is used only to make a filesys‐
304 tem image. If the value is omitted then 1 is as‐
305 sumed.
306 size=value
308 This is used to specify the size of the data sec‐
309 tion. This suboption is required if -d file[=1] is
310 given. Otherwise, it is only needed if the filesys‐
311 tem should occupy less space than the size of the
312 special file.
313 The data section must be at least 300MB in size.
315 sunit=value
317 This is used to specify the stripe unit for a RAID
318 device or a logical volume. The value has to be
319 specified in 512-byte block units. Use the su subop‐
320 tion to specify the stripe unit size in bytes. This
321 suboption ensures that data allocations will be
322 stripe unit aligned when the current end of file is
323 being extended and the file size is larger than
324 512KiB. Also inode allocations and the internal log
325 will be stripe unit aligned.
326 su=value
328 This is an alternative to using sunit. The su sub‐
329 option is used to specify the stripe unit for a RAID
330 device or a striped logical volume. The value has to
331 be specified in bytes, (usually using the m or g
332 suffixes). This value must be a multiple of the
333 filesystem block size.
334 swidth=value
336 This is used to specify the stripe width for a RAID
337 device or a striped logical volume. The value has to
338 be specified in 512-byte block units. Use the sw
339 suboption to specify the stripe width size in bytes.
340 This suboption is required if -d sunit has been
341 specified and it has to be a multiple of the -d
342 sunit suboption.
343 sw=value
345 suboption is an alternative to using swidth. The sw
346 suboption is used to specify the stripe width for a
347 RAID device or striped logical volume. The value is
348 expressed as a multiplier of the stripe unit, usu‐
349 ally the same as the number of stripe members in the
350 logical volume configuration, or data disks in a
351 RAID device.
352 When a filesystem is created on a block device,
354 mkfs.xfs will automatically query the block device
355 for appropriate sunit and swidth values if the block
356 device and the filesystem size would be larger than
357 1GB.
358 noalign
360 This option disables automatic geometry detection
361 and creates the filesystem without stripe geometry
362 alignment even if the underlying storage device pro‐
363 vides this information.
364 rtinherit=value
366 If value is set to 1, all inodes created by mkfs.xfs
367 will be created with the realtime flag set. The de‐
368 fault is 0. Directories will pass on this flag to
369 newly created regular files and directories.
370 projinherit=value
372 All inodes created by mkfs.xfs will be assigned the
373 project quota id provided in value. Directories
374 will pass on the project id to newly created regular
375 files and directories.
376 extszinherit=value
378 All inodes created by mkfs.xfs will have this value
379 extent size hint applied. The value must be pro‐
380 vided in units of filesystem blocks. Directories
381 will pass on this hint to newly created regular
382 files and directories.
383 daxinherit=value
385 If value is set to 1, all inodes created by mkfs.xfs
386 will be created with the DAX flag set. The default
387 is 0. Directories will pass on this flag to newly
388 created regular files and directories. By default,
389 mkfs.xfs will not enable DAX mode.
390 -f Force overwrite when an existing filesystem is detected on the
392 device. By default, mkfs.xfs will not write to the device if it
393 suspects that there is a filesystem or partition table on the
394 device already.
395 -i inode_options
397 Section Name: [inode]
398 This option specifies the inode size of the filesystem, and
399 other inode allocation parameters. The XFS inode contains a
400 fixed-size part and a variable-size part. The variable-size
401 part, whose size is affected by this option, can contain: direc‐
402 tory data, for small directories; attribute data, for small at‐
403 tribute sets; symbolic link data, for small symbolic links; the
404 extent list for the file, for files with a small number of ex‐
405 tents; and the root of a tree describing the location of extents
406 for the file, for files with a large number of extents.
407 The valid inode_options are:
409 size=value | perblock=value
411 The inode size is specified either as a value in
412 bytes with size= or as the number fitting in a
413 filesystem block with perblock=. The minimum (and
414 default) value is 256 bytes without crc, 512 bytes
415 with crc enabled. The maximum value is 2048 (2 KiB)
416 subject to the restriction that the inode size can‐
417 not exceed one half of the filesystem block size.
418 XFS uses 64-bit inode numbers internally; however,
420 the number of significant bits in an inode number is
421 affected by filesystem geometry. In practice,
422 filesystem size and inode size are the predominant
423 factors. The Linux kernel (on 32 bit hardware plat‐
424 forms) and most applications cannot currently handle
425 inode numbers greater than 32 significant bits, so
426 if no inode size is given on the command line,
427 mkfs.xfs will attempt to choose a size such that in‐
428 ode numbers will be < 32 bits. If an inode size is
429 specified, or if a filesystem is sufficiently large,
430 mkfs.xfs will warn if this will create inode numbers
431 > 32 significant bits.
432 maxpct=value
434 This specifies the maximum percentage of space in
435 the filesystem that can be allocated to inodes. The
436 default value is 25% for filesystems under 1TB, 5%
437 for filesystems under 50TB and 1% for filesystems
438 over 50TB.
439 Setting the value to 0 means that essentially all of
441 the filesystem can become inode blocks (subject to
442 possible inode32 mount option restrictions, see
443 xfs(5) for details.)
444 This value can be modified with xfs_growfs(8).
446 align[=value]
448 This is used to specify that inode allocation is or
449 is not aligned. The value is either 0 or 1, with 1
450 signifying that inodes are allocated aligned. If
451 the value is omitted, 1 is assumed. The default is
452 that inodes are aligned. Aligned inode access is
453 normally more efficient than unaligned access;
454 alignment must be established at the time the
455 filesystem is created, since inodes are allocated at
456 that time. This option can be used to turn off in‐
457 ode alignment when the filesystem needs to be mount‐
458 able by a version of IRIX that does not have the in‐
459 ode alignment feature (any release of IRIX before
460 6.2, and IRIX 6.2 without XFS patches).
461 This option is only tunable on the deprecated V4
463 format.
464 attr=value
466 This is used to specify the version of extended at‐
467 tribute inline allocation policy to be used. By de‐
468 fault, this is 2, which uses an efficient algorithm
469 for managing the available inline inode space be‐
470 tween attribute and extent data.
471 The previous version 1, which has fixed regions for
473 attribute and extent data, is kept for backwards
474 compatibility with kernels older than version
475 2.6.16.
476 This option is only tunable on the deprecated V4
478 format.
479 projid32bit[=value]
481 This is used to enable 32bit quota project identi‐
482 fiers. The value is either 0 or 1, with 1 signifying
483 that 32bit projid are to be enabled. If the value
484 is omitted, 1 is assumed. (This default changed in
485 release version 3.2.0.)
486 This option is only tunable on the deprecated V4
488 format.
489 sparse[=value]
491 Enable sparse inode chunk allocation. The value is
492 either 0 or 1, with 1 signifying that sparse alloca‐
493 tion is enabled. If the value is omitted, 1 is as‐
494 sumed. Sparse inode allocation is disabled by de‐
495 fault. This feature is only available for filesys‐
496 tems formatted with -m crc=1.
497 When enabled, sparse inode allocation allows the
499 filesystem to allocate smaller than the standard
500 64-inode chunk when free space is severely limited.
501 This feature is useful for filesystems that might
502 fragment free space over time such that no free ex‐
503 tents are large enough to accommodate a chunk of 64
504 inodes. Without this feature enabled, inode alloca‐
505 tions can fail with out of space errors under severe
506 fragmented free space conditions.
507 nrext64[=value]
509 Extend maximum values of inode data and attr fork
510 extent counters from 2^31 - 1 and 2^15 - 1 to 2^48 -
511 1 and 2^32 - 1 respectively. If the value is omit‐
512 ted, 1 is assumed. This feature is disabled by de‐
513 fault. This feature is only available for filesys‐
514 tems formatted with -m crc=1.
515 -l log_section_options
518 Section Name: [log]
519 These options specify the location, size, and other parameters
520 of the log section of the filesystem. The valid log_section_op‐
521 tions are:
522 agnum=value
524 If the log is internal, allocate it in this AG.
525 internal[=value]
527 This is used to specify that the log section is a
528 piece of the data section instead of being another
529 device or logical volume. The value is either 0 or
530 1, with 1 signifying that the log is internal. If
531 the value is omitted, 1 is assumed.
532 logdev=device
534 This is used to specify that the log section should
535 reside on the device separate from the data section.
536 The internal=1 and logdev options are mutually ex‐
537 clusive.
538 size=value
540 This is used to specify the size of the log section.
541 If the log is contained within the data section and
543 size isn't specified, mkfs.xfs will try to select a
544 suitable log size depending on the size of the
545 filesystem. The actual logsize depends on the
546 filesystem block size and the directory block size.
547 Otherwise, the size suboption is only needed if the
549 log section of the filesystem should occupy less
550 space than the size of the special file. The value
551 is specified in bytes or blocks, with a b suffix
552 meaning multiplication by the filesystem block size,
553 as described above. The overriding minimum value for
554 size is 512 blocks. With some combinations of
555 filesystem block size, inode size, and directory
556 block size, the minimum log size is larger than 512
557 blocks.
558 The log must be at least 64MB in size. The log can‐
560 not be more than 2GB in size.
561 version=value
563 This specifies the version of the log. The current
564 default is 2, which allows for larger log buffer
565 sizes, as well as supporting stripe-aligned log
566 writes (see the sunit and su options, below).
567 The previous version 1, which is limited to 32k log
569 buffers and does not support stripe-aligned writes,
570 is kept for backwards compatibility with very old
571 2.4 kernels.
572 This option is only tunable on the deprecated V4
574 format.
575 sunit=value
577 This specifies the alignment to be used for log
578 writes. The value has to be specified in 512-byte
579 block units. Use the su suboption to specify the log
580 stripe unit size in bytes. Log writes will be
581 aligned on this boundary, and rounded up to this
582 boundary. This gives major improvements in perfor‐
583 mance on some configurations such as software RAID5
584 when the sunit is specified as the filesystem block
585 size. The equivalent byte value must be a multiple
586 of the filesystem block size. Version 2 logs are au‐
587 tomatically selected if the log sunit suboption is
588 specified.
589 The su suboption is an alternative to using sunit.
591 su=value
593 This is used to specify the log stripe. The value
594 has to be specified in bytes, (usually using the s
595 or b suffixes). This value must be a multiple of the
596 filesystem block size. Version 2 logs are automati‐
597 cally selected if the log su suboption is specified.
598 lazy-count=value
600 This changes the method of logging various persis‐
601 tent counters in the superblock. Under metadata in‐
602 tensive workloads, these counters are updated and
603 logged frequently enough that the superblock updates
604 become a serialization point in the filesystem. The
605 value can be either 0 or 1.
606 With lazy-count=1, the superblock is not modified or
608 logged on every change of the persistent counters.
609 Instead, enough information is kept in other parts
610 of the filesystem to be able to maintain the persis‐
611 tent counter values without needed to keep them in
612 the superblock. This gives significant improvements
613 in performance on some configurations. The default
614 value is 1 (on) so you must specify lazy-count=0 if
615 you want to disable this feature for older kernels
616 which don't support it.
617 This option is only tunable on the deprecated V4
619 format.
620 -n naming_options
622 Section Name: [naming]
623 These options specify the version and size parameters for the
624 naming (directory) area of the filesystem. The valid naming_op‐
625 tions are:
626 size=value
628 The directory block size is specified with a value
629 in bytes. The block size must be a power of 2 and
630 cannot be less than the filesystem block size. The
631 default size value for version 2 directories is 4096
632 bytes (4 KiB), unless the filesystem block size is
633 larger than 4096, in which case the default value is
634 the filesystem block size. For version 1 directo‐
635 ries the block size is the same as the filesystem
636 block size.
637 version=value
639 The naming (directory) version value can be either 2
640 or 'ci', defaulting to 2 if unspecified. With ver‐
641 sion 2 directories, the directory block size can be
642 any power of 2 size from the filesystem block size
643 up to 65536.
644 The version=ci option enables ASCII only case-insen‐
646 sitive filename lookup and version 2 directories.
647 Filenames are case-preserving, that is, the names
648 are stored in directories using the case they were
649 created with.
650 Note: Version 1 directories are not supported.
652 ftype=value
654 This feature allows the inode type to be stored in
655 the directory structure so that the readdir(3) and
656 getdents(2) do not need to look up the inode to de‐
657 termine the inode type.
658 The value is either 0 or 1, with 1 signifying that
660 filetype information will be stored in the directory
661 structure. The default value is 1.
662 When CRCs are enabled (the default), the ftype func‐
664 tionality is always enabled, and cannot be turned
665 off.
666 In other words, this option is only tunable on the
668 deprecated V4 format.
669 -p protofile
671 If the optional -p protofile argument is given, mkfs.xfs uses
672 protofile as a prototype file and takes its directions from that
673 file. The blocks and inodes specifiers in the protofile are
674 provided for backwards compatibility, but are otherwise unused.
675 The syntax of the protofile is defined by a number of tokens
676 separated by spaces or newlines. Note that the line numbers are
677 not part of the syntax but are meant to help you in the follow‐
678 ing discussion of the file contents.
679 1 /stand/diskboot
681 2 4872 110
682 3 d--777 3 1
683 4 usr d--777 3 1
684 5 sh ---755 3 1 /bin/sh
685 6 ken d--755 6 1
686 7 $
687 8 b0 b--644 3 1 0 0
688 9 c0 c--644 3 1 0 0
689 10 fifo p--644 3 1
690 11 slink l--644 3 1 /a/symbolic/link
691 12 : This is a comment line
692 13 $
693 14 $
694 Line 1 is a dummy string. (It was formerly the bootfilename.)
696 It is present for backward compatibility; boot blocks are not
697 used on SGI systems.
698 Note that some string of characters must be present as the first
700 line of the proto file to cause it to be parsed correctly; the
701 value of this string is immaterial since it is ignored.
702 Line 2 contains two numeric values (formerly the numbers of
704 blocks and inodes). These are also merely for backward compati‐
705 bility: two numeric values must appear at this point for the
706 proto file to be correctly parsed, but their values are immate‐
707 rial since they are ignored.
708 The lines 3 through 11 specify the files and directories you
710 want to include in this filesystem. Line 3 defines the root di‐
711 rectory. Other directories and files that you want in the
712 filesystem are indicated by lines 4 through 6 and lines 8
713 through 10. Line 11 contains symbolic link syntax.
714 Notice the dollar sign ($) syntax on line 7. This syntax directs
716 the mkfs.xfs command to terminate the branch of the filesystem
717 it is currently on and then continue from the directory speci‐
718 fied by the next line, in this case line 8. It must be the last
719 character on a line. The colon on line 12 introduces a comment;
720 all characters up until the following newline are ignored. Note
721 that this means you cannot have a file in a prototype file whose
722 name contains a colon. The $ on lines 13 and 14 end the
723 process, since no additional specifications follow.
724 File specifications provide the following:
726 * file mode
728 * user ID
729 * group ID
730 * the file's beginning contents
731 A 6-character string defines the mode for a file. The first
733 character of this string defines the file type. The character
734 range for this first character is -bcdpl. A file may be a regu‐
735 lar file, a block special file, a character special file, direc‐
736 tory files, named pipes (first-in, first out files), and sym‐
737 bolic links. The second character of the mode string is used to
738 specify setuserID mode, in which case it is u. If setuserID
739 mode is not specified, the second character is -. The third
740 character of the mode string is used to specify the setgroupID
741 mode, in which case it is g. If setgroupID mode is not speci‐
742 fied, the third character is -. The remaining characters of the
743 mode string are a three digit octal number. This octal number
744 defines the owner, group, and other read, write, and execute
745 permissions for the file, respectively. For more information on
746 file permissions, see the chmod(1) command.
747 Following the mode character string are two decimal number to‐
749 kens that specify the user and group IDs of the file's owner.
750 In a regular file, the next token specifies the pathname from
752 which the contents and size of the file are copied. In a block
753 or character special file, the next token are two decimal num‐
754 bers that specify the major and minor device numbers. When a
755 file is a symbolic link, the next token specifies the contents
756 of the link.
757 When the file is a directory, the mkfs.xfs command creates the
759 entries dot (.) and dot-dot (..) and then reads the list of
760 names and file specifications in a recursive manner for all of
761 the entries in the directory. A scan of the protofile is always
762 terminated with the dollar ( $ ) token.
763 -q Quiet option. Normally mkfs.xfs prints the parameters of the
765 filesystem to be constructed; the -q flag suppresses this.
766 -r realtime_section_options
768 Section Name: [realtime]
769 These options specify the location, size, and other parameters
770 of the real-time section of the filesystem. The valid real‐
771 time_section_options are:
772 rtdev=device
774 This is used to specify the device which should con‐
775 tain the real-time section of the filesystem. The
776 suboption value is the name of a block device.
777 extsize=value
779 This is used to specify the size of the blocks in
780 the real-time section of the filesystem. This value
781 must be a multiple of the filesystem block size. The
782 minimum allowed size is the filesystem block size or
783 4 KiB (whichever is larger); the default size is the
784 stripe width for striped volumes or 64 KiB for non-
785 striped volumes; the maximum allowed size is 1 GiB.
786 The real-time extent size should be carefully chosen
787 to match the parameters of the physical media used.
788 size=value
790 This is used to specify the size of the real-time
791 section. This suboption is only needed if the real-
792 time section of the filesystem should occupy less
793 space than the size of the partition or logical vol‐
794 ume containing the section.
795 noalign
797 This option disables stripe size detection, enforc‐
798 ing a realtime device with no stripe geometry.
799 -s sector_size_options
801 Section Name: [sector]
802 This option specifies the fundamental sector size of the
803 filesystem. The valid sector_size_option is:
804 size=value
806 The sector size is specified with a value in bytes.
807 The default sector_size is 512 bytes. The minimum
808 value for sector size is 512; the maximum is 32768
809 (32 KiB). The sector_size must be a power of 2 size
810 and cannot be made larger than the filesystem block
811 size.
812 -L label
814 Set the filesystem label. XFS filesystem labels can be at most
815 12 characters long; if label is longer than 12 characters,
816 mkfs.xfs will not proceed with creating the filesystem. Refer
817 to the mount(8) and xfs_admin(8) manual entries for additional
818 information.
819 -N Causes the file system parameters to be printed out without re‐
821 ally creating the file system.
822 -K Do not attempt to discard blocks at mkfs time.
824 -V Prints the version number and exits.
826
828 The configuration file uses a basic INI format to specify sections and
829 options within a section. Section and option names are case sensitive.
830 Section names must not contain whitespace. Options are name-value
831 pairs, ended by the first whitespace in the line. Option names cannot
832 contain whitespace. Full line comments can be added by starting a line
833 with a # symbol. If values contain whitespace, then it must be quoted.
834 The following example configuration file sets the block size to 4096
836 bytes, turns on reverse mapping btrees and sets the inode size to 2048
837 bytes.
838 # Example mkfs.xfs configuration file
840 [block]
842 size=4k
843 [metadata]
845 rmapbt=1
846 [inode]
848 size=2048
849
852 xfs(5), mkfs(8), mount(8), xfs_info(8), xfs_admin(8).
853
855 With a prototype file, it is not possible to specify hard links.
856 mkfs.xfs(8)