1 .TH BTRFS 8 "" "btrfs" "btrfs"
3 .\" Man page written by Goffredo Baroncelli <kreijack@inwind.it> (Feb 2010)
6 btrfs \- control a btrfs filesystem
8 \fBbtrfs\fP \fBsubvolume snapshot\fP\fI [-r] <source> [<dest>/]<name>\fP
10 \fBbtrfs\fP \fBsubvolume delete\fP\fI <subvolume> [<subvolume>...]\fP
12 \fBbtrfs\fP \fBsubvolume create\fP\fI [<dest>/]<name>\fP
14 \fBbtrfs\fP \fBsubvolume list\fP\fI [-aprts] [-g [+|-]value] [-c [+|-]value] [--rootid=rootid,gen,ogen,path] <path>\fP
16 \fBbtrfs\fP \fBsubvolume set-default\fP\fI <id> <path>\fP
18 \fBbtrfs\fP \fBsubvolume get-default\fP\fI <path>\fP
20 \fBbtrfs\fP \fBsubvolume find-new\fP\fI <subvolume> <last_gen>\fP
22 \fBbtrfs\fP \fBfilesystem defragment\fP -c[zlib|lzo] [-l \fIlen\fR] \
23 [-s \fIstart\fR] [-t \fIsize\fR] -[vf] <\fIfile\fR>|<\fIdir\fR> \
24 [<\fIfile\fR>|<\fIdir\fR>...]
26 \fBbtrfs\fP \fBfilesystem sync\fP\fI <path> \fP
28 \fBbtrfs\fP \fBfilesystem resize\fP\fI [devid:][+/\-]<size>[gkm]|[devid:]max <filesystem>\fP
30 \fBbtrfs\fP \fBfilesystem label\fP\fI <dev> [newlabel]\fP
32 \fBbtrfs\fP \fBfilesystem balance\fP\fI <path> \fP
34 \fBbtrfs\fP \fBdevice scan\fP\fI [--all-devices|<device> [<device>...]]\fP
36 \fBbtrfs\fP \fBdevice stats\fP [-z] {\fI<path>\fP|\fI<device>\fP}
38 \fBbtrfs\fP \fBdevice add\fP\fI <device> [<device>...] <path> \fP
40 \fBbtrfs\fP \fBdevice delete\fP\fI <device> [<device>...] <path> \fP
42 \fBbtrfs\fP \fBreplace start\fP \fI[-Bfr] <srcdev>|<devid> <targetdev> <path>\fP
44 \fBbtrfs\fP \fBreplace status\fP \fI[-1] <path>\fP
46 \fBbtrfs\fP \fBreplace cancel\fP \fI<path>\fP
48 \fBbtrfs\fP \fBscrub start\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
50 \fBbtrfs\fP \fBscrub cancel\fP {\fI<path>\fP|\fI<device>\fP}
52 \fBbtrfs\fP \fBscrub resume\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
54 \fBbtrfs\fP \fBscrub status\fP [-d] {\fI<path>\fP|\fI<device>\fP}
56 \fBbtrfs\fP \fBinspect-internal inode-resolve\fP [-v] \fI<inode>\fP \fI<path>\fP
58 \fBbtrfs\fP \fBinspect-internal logical-resolve\fP
59 [-Pv] [-s size] \fI<logical>\fP \fI<path>\fP
61 \fBbtrfs\fP \fBhelp|\-\-help \fP\fI\fP
63 \fBbtrfs\fP \fB<command> \-\-help \fP\fI\fP
67 is used to control the filesystem and the files and directories stored. It is
68 the tool to create or destroy a snapshot or a subvolume for the
69 filesystem, to defrag a file or a directory, flush the data to the disk,
70 to resize the filesystem, to scan the device.
72 It is possible to abbreviate the commands unless the commands are ambiguous.
73 For example: it is possible to run
76 .I btrfs subvolume snapshot.
79 is not allowed, because
81 may be interpreted both as
87 returns filesystem sync
88 If a command is terminated by
90 , the detailed help is showed. If the passed command matches more commands,
91 detailed help of all the matched commands is showed. For example
100 \fBsubvolume snapshot\fR\fI [-r] <source> [<dest>/]<name>\fR
101 Create a writable/readonly snapshot of the subvolume \fI<source>\fR with the
102 name \fI<name>\fR in the \fI<dest>\fR directory. If \fI<source>\fR is not a
103 subvolume, \fBbtrfs\fR returns an error. If \fI-r\fR is given, the snapshot
107 \fBsubvolume delete\fR\fI <subvolume> [<subvolume>...]\fR
108 Delete the subvolume \fI<subvolume>\fR. If \fI<subvolume>\fR is not a
109 subvolume, \fBbtrfs\fR returns an error.
112 \fBsubvolume create\fR\fI [<dest>/]<name>\fR
113 Create a subvolume in \fI<dest>\fR (or in the current directory if
114 \fI<dest>\fR is omitted).
117 \fBsubvolume list\fR\fI [-aprts][-g [+|-]value] [-c [+|-]value] [--sort=gen,ogen,rootid,path] <path>\fR
119 List the subvolumes present in the filesystem \fI<path>\fR. For every
120 subvolume the following information is shown by default.
121 ID <ID> top level <ID> path <path>
122 where path is the relative path of the subvolume to the \fItop level\fR
125 The subvolume's ID may be used by the \fBsubvolume set-default\fR command, or
126 at mount time via the \fIsubvol=\fR option.
127 If \fI-p\fR is given, then \fIparent <ID>\fR is added to the output between ID
128 and top level. The parent's ID may be used at mount time via the
129 \fIsubvolrootid=\fR option.
131 \fB-t\fP print the result as a table.
133 \fB-a\fP print all the subvolumes in the filesystem.
135 \fB-r\fP only readonly subvolumes in the filesystem wille be listed.
137 \fB-s\fP only snapshot subvolumes in the filesystem will be listed.
140 list subvolumes in the filesystem that its generation is
141 >=, <= or = value. '+' means >= value, '-' means <= value, If there is
142 neither '+' nor '-', it means = value.
145 list subvolumes in the filesystem that its ogeneration is
146 >=, <= or = value. The usage is the same to '-g' option.
148 \fB--sort=gen,ogen,path,rootid\fP
149 list subvolumes in order by specified items.
150 you can add '+' or '-' in front of each items, '+' means ascending,'-'
151 means descending. The default is ascending.
153 for \fB--sort\fP you can combine some items together by ',', just like
154 \f--sort=+ogen,-gen,path,rootid\fR.
158 \fBsubvolume set-default\fR\fI <id> <path>\fR
159 Set the subvolume of the filesystem \fI<path>\fR which is mounted as
160 \fIdefault\fR. The subvolume is identified by \fI<id>\fR, which
161 is returned by the \fBsubvolume list\fR command.
164 \fBsubvolume get-default\fR\fI <path>\fR
165 Get the default subvolume of the filesystem \fI<path>\fR. The output format
166 is similar to \fBsubvolume list\fR command.
169 \fBsubvolume find-new\fR\fI <subvolume> <last_gen>\fR
170 List the recently modified files in a subvolume, after \fI<last_gen>\fR ID.
173 \fBfilesystem defragment\fP -c[zlib|lzo] [-l \fIlen\fR] [-s \fIstart\fR] \
174 [-t \fIsize\fR] -[vf] <\fIfile\fR>|<\fIdir\fR> [<\fIfile\fR>|<\fIdir\fR>...]
176 Defragment file data and/or directory metadata. To defragment all files in a
177 directory you have to specify each one on its own or use your shell wildcards.
179 The start position and the number of bytes to defragment can be specified by
180 \fIstart\fR and \fIlen\fR. Any extent bigger than threshold will be
181 considered already defragged. Use 0 to take the kernel default, and use 1 to
182 say every single extent must be rewritten. You can also turn on compression in
183 defragment operations.
187 \fB-c\fP compress file contents while defragmenting
189 \fB-f\fP flush filesystem after defragmenting
191 \fB-s start\fP defragment only from byte \fIstart\fR onward
193 \fB-l len\fP defragment only up to \fIlen\fR bytes
195 \fB-t size\fP defragment only files at least \fIsize\fR bytes big
197 For \fBstart\fP, \fBlen\fP, \fBsize\fP it is possible to append a suffix
198 like \fBk\fP for 1 KBytes, \fBm\fP for 1 MBytes...
200 NOTE: defragmenting with kernels up to 2.6.37 will unlink COW-ed copies of data,
201 don't use it if you use snapshots, have de-duplicated your data or made
202 copies with \fBcp --reflink\fP.
205 \fBfilesystem sync\fR\fI <path> \fR
206 Force a sync for the filesystem identified by \fI<path>\fR.
210 .\" Some wording are extracted by the resize2fs man page
213 \fBfilesystem resize\fR\fI [devid:][+/\-]<size>[gkm]|[devid:]max <path>\fR
214 Resize a filesystem identified by \fI<path>\fR for the underlying device
215 \fIdevid\fR. The \fIdevid\fR can be found with \fBbtrfs filesystem show\fR and
216 defaults to 1 if not specified.
217 The \fI<size>\fR parameter specifies the new size of the filesystem.
218 If the prefix \fI+\fR or \fI\-\fR is present the size is increased or decreased
219 by the quantity \fI<size>\fR.
220 If no units are specified, the unit of the \fI<size>\fR parameter defaults to
221 bytes. Optionally, the size parameter may be suffixed by one of the following
222 units designators: 'K', 'M', or 'G', kilobytes, megabytes, or gigabytes,
225 If 'max' is passed, the filesystem will occupy all available space on the
228 The \fBresize\fR command \fBdoes not\fR manipulate the size of underlying
229 partition. If you wish to enlarge/reduce a filesystem, you must make sure you
230 can expand the partition before enlarging the filesystem and shrink the
231 partition after reducing the size of the filesystem. This can done using
232 \fBfdisk(8)\fR or \fBparted(8)\fR to delete the existing partition and recreate
233 it with the new desired size. When recreating the partition make sure to use
234 the same starting disk cylinder as before.
237 \fBfilesystem label\fP\fI <dev> [newlabel]\fP
238 Show or update the label of a filesystem. \fI<dev>\fR is used to identify the
240 If a \fInewlabel\fR optional argument is passed, the label is changed. The
241 following constraints exist for a label:
243 - the maximum allowable length shall be less or equal than 256 chars
245 - the label shall not contain the '/' or '\\' characters.
247 NOTE: Currently there are the following limitations:
249 - the filesystem has to be unmounted
251 - the filesystem should not have more than one device.
254 \fBfilesystem show\fR [--all-devices|<uuid>|<label>]\fR
255 Show the btrfs filesystem with some additional info. If no \fIUUID\fP or
256 \fIlabel\fP is passed, \fBbtrfs\fR show info of all the btrfs filesystem.
257 If \fB--all-devices\fP is passed, all the devices under /dev are scanned;
258 otherwise the devices list is extracted from the /proc/partitions file.
261 \fBfilesystem balance\fR \fI<path>\fR
262 Balance the chunks of the filesystem identified by \fI<path>\fR
266 \fBdevice stats\fP [-z] {\fI<path>\fP|\fI<device>\fP}
267 Read and print the device IO stats for all devices of the filesystem
268 identified by \fI<path>\fR or for a single \fI<device>\fR.
274 Reset stats to zero after reading them.
278 \fBdevice add\fR\fI <dev> [<dev>..] <path>\fR
279 Add device(s) to the filesystem identified by \fI<path>\fR.
282 \fBdevice delete\fR\fI <dev> [<dev>..] <path>\fR
283 Remove device(s) from a filesystem identified by \fI<path>\fR.
286 \fBdevice scan\fR \fI[--all-devices|<device> [<device>...]\fR
287 If one or more devices are passed, these are scanned for a btrfs filesystem.
288 If no devices are passed, \fBbtrfs\fR scans all the block devices listed
289 in the /proc/partitions file.
290 Finally, if \fB--all-devices\fP is passed, all the devices under /dev are
294 \fBreplace start\fR \fI[-Bfr] <srcdev>|<devid> <targetdev> <path>\fR
295 Replace device of a btrfs filesystem.
296 On a live filesystem, duplicate the data to the target device which
297 is currently stored on the source device. If the source device is not
298 available anymore, or if the \fB-r\fR option is set, the data is built
299 only using the RAID redundancy mechanisms. After completion of the
300 operation, the source device is removed from the filesystem.
301 If the \fIsrcdev\fR is a numerical value, it is assumed to be the device id
302 of the filesystem which is mounted at mount_point, otherwise is is
303 the path to the source device. If the source device is disconnected,
304 from the system, you have to use the \fIdevid\fR parameter format.
305 The targetdev needs to be same size or larger than the \fIsrcdev\fR.
311 only read from \fIsrcdev\fR if no other zero-defect mirror exists (enable
312 this if your drive has lots of read errors, the access would be very slow)
315 force using and overwriting \fItargetdev\fR even if it looks like
316 containing a valid btrfs filesystem. A valid filesystem is
317 assumed if a btrfs superblock is found which contains a
318 correct checksum. Devices which are currently mounted are
319 never allowed to be used as the \fItargetdev\fR
326 \fBreplace status\fR \fI[-1] <path>\fR
327 Print status and progress information of a running device replace operation.
333 print once instead of print continously until the replace
334 operation finishes (or is canceled)
338 \fBreplace cancel\fR \fI<path>\fR
339 Cancel a running device replace operation.
342 \fBscrub start\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
343 Start a scrub on all devices of the filesystem identified by \fI<path>\fR or on
344 a single \fI<device>\fR. Without options, scrub is started as a background
345 process. Progress can be obtained with the \fBscrub status\fR command. Scrubbing
346 involves reading all data from all disks and verifying checksums. Errors are
347 corrected along the way if possible.
352 Do not background and print scrub statistics when finished.
354 Print separate statistics for each device of the filesystem (-B only).
356 Quiet. Omit error messages and statistics.
358 Read only mode. Do not attempt to correct anything.
360 Scrub unused space as well. (NOT IMPLEMENTED)
364 \fBscrub cancel\fP {\fI<path>\fP|\fI<device>\fP}
365 If a scrub is running on the filesystem identified by \fI<path>\fR, cancel it.
366 Progress is saved in the scrub progress file and scrubbing can be resumed later
367 using the \fBscrub resume\fR command.
368 If a \fI<device>\fR is given, the corresponding filesystem is found and
369 \fBscrub cancel\fP behaves as if it was called on that filesystem.
372 \fBscrub resume\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
373 Resume a canceled or interrupted scrub cycle on the filesystem identified by
374 \fI<path>\fR or on a given \fI<device>\fR. Does not start a new scrub if the
375 last scrub finished successfully.
380 see \fBscrub start\fP.
384 \fBscrub status\fP [-d] {\fI<path>\fP|\fI<device>\fP}
385 Show status of a running scrub for the filesystem identified by \fI<path>\fR or
386 for the specified \fI<device>\fR.
387 If no scrub is running, show statistics of the last finished or canceled scrub
388 for that filesystem or device.
393 Print separate statistics for each device of the filesystem.
397 \fBinspect-internal inode-resolve\fP [-v] \fI<inode>\fP \fI<path>\fP
398 Resolves an <inode> in subvolume <path> to all filesystem paths.
403 verbose mode. print count of returned paths and ioctl() return value
407 \fBinspect-internal logical-resolve\fP [-Pv] [-s bufsize] \fI<logical>\fP \fI<path>\fP
408 Resolves a <logical> address in the filesystem mounted at <path> to all inodes.
409 By default, each inode is then resolved to a file system path (similar to the
410 \fBinode-resolve\fP subcommand).
415 skip the path resolving and print the inodes instead
417 verbose mode. print count of returned paths and all ioctl() return values
419 set inode container's size. This is used to increase inode container's size in case it is
420 not enough to read all the resolved results. The max value one can set is 64k.
424 \fBbtrfs\fR returns a zero exist status if it succeeds. Non zero is returned in
429 is part of btrfs-progs. Btrfs filesystem is currently under heavy development,
430 and not suitable for any uses other than benchmarking and review.
431 Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for