# btrfs-filesystem - command group that primarily does work on the whole fi... - man(8) - [phpMan]

[_BTRFS-FILESYSTEM_(8)](https://www.chedong.com/phpMan.php/man/BTRFS-FILESYSTEM/8/markdown)                             BTRFS                            [_BTRFS-FILESYSTEM_(8)](https://www.chedong.com/phpMan.php/man/BTRFS-FILESYSTEM/8/markdown)

## NAME
       btrfs-filesystem - command group that primarily does work on the whole filesystems

## SYNOPSIS
       **btrfs filesystem **<subcommand> <args>

## DESCRIPTION
       **btrfs  filesystem  **is used to perform several whole filesystem level tasks, including all the
       regular filesystem operations like resizing, space stats, label setting/getting, and  defrag‐
       mentation.  There  are other whole filesystem tasks like scrub or balance that are grouped in
       separate commands.

## SUBCOMMAND
### df [options] <path>
              Show a terse summary information about allocation of block  group  types  of  a  given
              mount  point.  The original purpose of this command was a debugging helper. The output
              needs to be further interpreted and is not suitable for quick overview.

              An example with description:

              • device size: _1.9TiB_, one device, no RAID

              • filesystem size: _1.9TiB_

              • created with: **mkfs.btrfs -d single -m single**

                 $ btrfs filesystem df /path
                 Data, single: total=1.15TiB, used=1.13TiB
                 System, single: total=32.00MiB, used=144.00KiB
                 Metadata, single: total=12.00GiB, used=6.45GiB
                 GlobalReserve, single: total=512.00MiB, used=0.00B

              • _Data_, _System_ and _Metadata_ are separate block group types.  _GlobalReserve_ is an arti‐
                ficial and internal emergency space, see below.

              • _single_ -- the allocation profile, defined at mkfs time

              • _total_ -- sum of space reserved for all allocation profiles of the given  type,  i.e.
                all Data/single. Note that it's not total size of filesystem.

              • _used_ -- sum of used space of the above, i.e. file extents, metadata blocks

              _GlobalReserve_ is an artificial and internal emergency space. It is used e.g.  when the
              filesystem  is  full.  Its _total_ size is dynamic based on the filesystem size, usually
              not larger than 512MiB, _used_ may fluctuate.

              The GlobalReserve is a portion of Metadata. In case the  filesystem  metadata  is  ex‐
              hausted, _GlobalReserve/total_ _+_ _Metadata/used_ _=_ _Metadata/total_. Otherwise there appears
              to be some unused space of Metadata.

              **Options**

              **-b|--raw**
                     raw numbers in bytes, without the _B_ suffix

              **-h|--human-readable**
                     print human friendly numbers, base 1024, this is the default

              **-H     **print human friendly numbers, base 1000

              **--iec  **select the 1024 base for the following options, according to the IEC standard

              **--si   **select the 1000 base for the following options, according to the SI standard

              **-k|--kbytes**
                     show sizes in KiB, or kB with --si

              **-m|--mbytes**
                     show sizes in MiB, or MB with --si

              **-g|--gbytes**
                     show sizes in GiB, or GB with --si

              **-t|--tbytes**
                     show sizes in TiB, or TB with --si

              If conflicting options are passed, the last one takes precedence.

### defragment [options] <file>|<dir> [<file>|<dir>...]
              Defragment file data on a mounted filesystem. Requires kernel 2.6.33 and newer.

              If _-r_ is passed, files in dir will be defragmented recursively (not descending to sub‐
              volumes,  mount  points and directory symlinks).  The start position and the number of
              bytes to defragment can be specified by start and length using _-s_ and _-l_  options  be‐
              low.   Extents  bigger than value given by _-t_ will be skipped, otherwise this value is
              used as a target extent size, but is only advisory and may not be reached if the  free
              space  is  too  fragmented.  Use 0 to take the kernel default, which is 256KiB but may
              change in the future.  You can also turn on compression in defragment operations.

              **WARNING:**
                 Defragmenting with Linux kernel versions < 3.9 or ≥ 3.14-rc2 as well as with  Linux
                 stable  kernel versions ≥ 3.10.31, ≥ 3.12.12 or ≥ 3.13.4 will break up the reflinks
                 of COW data (for example files copied with **cp --reflink**, snapshots or de-duplicated
                 data).  This may cause considerable increase of space usage depending on the broken
                 up reflinks.

              **NOTE:**
                 Directory arguments without _-r_ do not defragment files recursively but will defrag‐
                 ment certain internal trees (extent tree and the subvolume  tree).  This  has  been
                 confusing and could be removed in the future.

              For  _start_,  _len_, _size_ it is possible to append units designator: _K_, _M_, _G_, _T_, _P_, or _E_,
              which represent KiB, MiB, GiB, TiB, PiB, or EiB, respectively (case does not matter).

              **Options**

              **-c[<algo>]**
                     compress file contents while defragmenting. Optional argument selects the  com‐
                     pression algorithm, _zlib_ (default), _lzo_ or _zstd_. Currently it's not possible to
                     select no compression. See also section _EXAMPLES_.

              **-r     **defragment  files recursively in given directories, does not descend to subvol‐
                     umes or mount points

              **-f     **flush data for each file before going to the next file.

                     This will limit the amount of dirty data to current file, otherwise the  amount
                     accumulates  from  several  files  and will increase system load. This can also
                     lead to ENOSPC if there's too much dirty data to write and it's not possible to
                     make the reservations for the new data (i.e. how the COW design works).

              **-s <start>[kKmMgGtTpPeE]**
                     defragmentation will start from the given offset, default  is  beginning  of  a
                     file

              **-l <len>[kKmMgGtTpPeE]**
                     defragment only up to _len_ bytes, default is the file size

              **-t <size>[kKmMgGtTpPeE]**
                     target extent size, do not touch extents bigger than _size_, default: 32MiB

                     The  value  is  only advisory and the final size of the extents may differ, de‐
                     pending on the state of the free space  and  fragmentation  or  other  internal
                     logic. Reasonable values are from tens to hundreds of megabytes.

              **--step _**SIZE_
                     Perform defragmention in the range in SIZE steps and flush (_-f_) after each one.
                     The  range  is  default  (the whole file) or given by _-s_ and _-l_, split into the
                     steps or done in one go if the step is larger. Minimum range size is 256KiB.

### -v     (deprecated)

### du [options] <path> [<path>..]
              Calculate disk usage of the target files using FIEMAP. For individual files,  it  will
              report  a  count of total bytes, and exclusive (not shared) bytes. We also calculate a
              'set shared' value which is described below.

              Each argument to **btrfs filesystem du **will have a _set_ _shared_ value calculated  for  it.
              We  define  each _set_ as those files found by a recursive search of an argument (recur‐
              sion descends to subvolumes but not mount points). The _set_ _shared_ value then is a  sum
              of all shared space referenced by the set.

              _set_  _shared_ takes into account overlapping shared extents, hence it isn't as simple as
              adding up shared extents.

              **Options**

              **-s|--summarize**
                     display only a total for each argument

              **--raw  **raw numbers in bytes, without the _B_ suffix.

              **--human-readable**
                     print human friendly numbers, base 1024, this is the default

              **--iec  **select the 1024 base for the following options, according to the IEC standard.

              **--si   **select the 1000 base for the following options, according to the SI standard.

              **--kbytes**
                     show sizes in KiB, or kB with --si.

              **--mbytes**
                     show sizes in MiB, or MB with --si.

              **--gbytes**
                     show sizes in GiB, or GB with --si.

              **--tbytes**
                     show sizes in TiB, or TB with --si.

### label [<device>|<mountpoint>] [<newlabel>]
              Show or update the label of a filesystem. This works on  a  mounted  filesystem  or  a
              filesystem image.

              The  _newlabel_  argument is optional. Current label is printed if the argument is omit‐
              ted.

              **NOTE:**
                 The maximum allowable length shall be less than 256 chars and must  not  contain  a
                 newline. The trailing newline is stripped automatically.

### mkswapfile [-s size] file
              Create  a  new file that's suitable and formatted as a swapfile. Default size is 2GiB,
              fixed page size 4KiB, minimum size is 40KiB.

              A swapfile must be created in a specific way: NOCOW and preallocated.  Subvolume  con‐
              taining a swapfile cannot be snapshotted and blocks of an activated swapfile cannot be
              balanced.

              Swapfile  creation  can be achieved by standalone commands too. Activation needs to be
              done by command [**swapon(8)](https://www.chedong.com/phpMan.php/man/swapon/8/markdown)**. See also command **btrfs  inspect-internal  map-swapfile  **and
              the _Swapfile_ _feature_ description.

              **NOTE:**
                 The  command  is  a  simplified version of 'mkswap', if you want to set label, page
                 size, or other parameters please use 'mkswap' proper.

              **Options**

              **-s|--size SIZE**
                     Create swapfile of a given size SIZE (accepting k/m/g/e/p suffix).

              **-U|--uuid UUID**
                     specify UUID to use, or a  special  value:  clear  (all  zeros),  random,  time
                     (time-based random)

### resize [options] [<devid>:][+/-]<size>[kKmMgGtTpPeE]|[<devid>:]max <path>
              Resize  a mounted filesystem identified by _path_. A particular device can be resized by
              specifying a _devid_.

              **WARNING:**
                 If _path_ is a file containing a BTRFS image then resize does not  work  as  expected
                 and does not resize the image. This would resize the underlying filesystem instead.

              The _devid_ can be found in the output of **btrfs filesystem show **and defaults to 1 if not
              specified.   The _size_ parameter specifies the new size of the filesystem.  If the pre‐
              fix _+_ or _-_ is present the size is increased or decreased by the quantity _size_.  If  no
              units  are  specified, bytes are assumed for _size_.  Optionally, the size parameter may
              be suffixed by one of the following unit designators: _K_, _M_, _G_, _T_, _P_, or _E_, which  rep‐
              resent KiB, MiB, GiB, TiB, PiB, or EiB, respectively (case does not matter).

              If  _max_  is  passed,  the filesystem will occupy all available space on the device re‐
              specting _devid_ (remember, devid 1 by default).

              The resize command does not manipulate the size of underlying partition.  If you  wish
              to enlarge/reduce a filesystem, you must make sure you can expand the partition before
              enlarging  the  filesystem  and  shrink  the  partition after reducing the size of the
              filesystem.  This can done using [**fdisk(8)](https://www.chedong.com/phpMan.php/man/fdisk/8/markdown) **or [**parted(8)](https://www.chedong.com/phpMan.php/man/parted/8/markdown) **to delete the  existing  parti‐
              tion  and  recreate  it with the new desired size.  When recreating the partition make
              sure to use the same starting partition offset as before.

              Growing is usually instant as it only updates the size. However, shrinking could  take
              a long time if there are data in the device area that's beyond the new end. Relocation
              of the data takes time.

              See also section _EXAMPLES_.

              **Options**

              **--enqueue**
                     wait if there's another exclusive operation running, otherwise continue

### show [options] [<path>|<uuid>|<device>|<label>]
              Show  the  btrfs  filesystem with some additional info about devices and space alloca‐
              tion.

              If no option none of _path_/_uuid_/_device_/_label_ is passed, information about all the BTRFS
              filesystems is shown, both mounted and unmounted.

              **Options**

              **-m|--mounted**
                     probe kernel for mounted BTRFS filesystems

              **-d|--all-devices**
                     scan all devices under **/dev**, otherwise the devices list is extracted  from  the
                     **/proc/partitions **file. This is a fallback option if there's no device node man‐
                     ager (like udev) available in the system.

              **--raw  **raw numbers in bytes, without the _B_ suffix

              **--human-readable**
                     print human friendly numbers, base 1024, this is the default

              **--iec  **select the 1024 base for the following options, according to the IEC standard

              **--si   **select the 1000 base for the following options, according to the SI standard

              **--kbytes**
                     show sizes in KiB, or kB with --si

              **--mbytes**
                     show sizes in MiB, or MB with --si

              **--gbytes**
                     show sizes in GiB, or GB with --si

              **--tbytes**
                     show sizes in TiB, or TB with --si

### sync <path>
              Force  a  sync of the filesystem at _path_, similar to the [**sync(1)](https://www.chedong.com/phpMan.php/man/sync/1/markdown) **command. In addition,
              it starts cleaning of deleted subvolumes. To wait for the subvolume deletion  to  com‐
              plete use the **btrfs subvolume sync **command.

### usage [options] <path> [<path>...]
              Show detailed information about internal filesystem usage. This is supposed to replace
              the **btrfs filesystem df **command in the long run.

              The  level of detail can differ if the command is run under a regular or the root user
              (due to use of restricted ioctl). For both there's a summary section with  information
              about space usage:

                 $ btrfs filesystem usage /path
                 WARNING: cannot read detailed chunk info, RAID5/6 numbers will be incorrect, run as root
                 Overall:
                     Device size:                   1.82TiB
                     Device allocated:              1.17TiB
                     Device unallocated:          669.99GiB
                     Device missing:                  0.00B
                     Device slack:                  1.00GiB
                     Used:                          1.14TiB
                     Free (estimated):            692.57GiB      (min: 692.57GiB)
                     Free (statfs, df)            692.57GiB
                     Data ratio:                       1.00
                     Metadata ratio:                   1.00
                     Global reserve:              512.00MiB      (used: 0.00B)
                     Multiple profiles:                  no

              • _Device_  _size_  --  sum  of raw device capacity available to the filesystem, note that
                this may not be the same as the total device size (the difference  is  accounted  as
                slack)

              • _Device_  _allocated_ -- sum of total space allocated for data/metadata/system profiles,
                this also accounts space reserved but not yet used for extents

              • _Device_ _unallocated_ -- the remaining unallocated space for future  allocations  (dif‐
                ference of the above two numbers)

              • _Device_ _missing_ -- sum of capacity of all missing devices

              • _Device_  _slack_ -- sum of slack space on all devices (difference between entire device
                size and the space occupied by filesystem)

              • _Used_ -- sum of the used space of data/metadata/system profiles,  not  including  the
                reserved space

              • _Free_  _(estimated)_  --  approximate size of the remaining free space usable for data,
                including currently allocated space and estimating  the  usage  of  the  unallocated
                space  based on the block group profiles, the _min_ is the lower bound of the estimate
                in case multiple profiles are present

              • _Free_ _(statfs,_ _df)_ -- the amount of space available  for  data  as  reported  by  the
                **statfs/statvfs  **syscall,  also  returned  as _Avail_ in the output of **df**. The value is
                calculated in a different way and may not match the estimate  in  some  cases  (e.g.
                multiple profiles).

              • _Data_  _ratio_  --  ratio of total space for data including redundancy or parity to the
                effectively usable data space, e.g. single is 1.0, RAID1 is 2.0 and for  RAID5/6  it
                depends on the number of devices

              • _Metadata_ _ratio_ -- ditto, for metadata

              • _Global_  _reserve_ -- portion of metadata currently used for global block reserve, used
                for emergency purposes (like deletion on a full filesystem)

              • _Multiple_ _profiles_ -- what block group types (data, metadata) have more than one pro‐
                file (single, raid1, ...), see [_btrfs(5)](https://www.chedong.com/phpMan.php/man/btrfs/5/markdown)_ section _FILESYSTEMS_ _WITH_ _MULTIPLE_ _PROFILES_.

              And on a zoned filesystem there are two more lines in the _Device_ section:

                 Device zone unusable:          5.13GiB
                 Device zone size:            256.00MiB

              • _Device_ _zone_ _unusable_ -- sum of of space that's been used in the past but now is  not
                due to COW and not referenced anymore, the chunks have to be reclaimed and zones re‐
                set to make it usable again

              • _Device_  _zone_ _size_ -- the reported zone size of the host-managed device, same for all
                devices

              The root user will also see stats broken down by block group types:

                 Data,single: Size:1.15TiB, Used:1.13TiB (98.26%)
                    /dev/sdb        1.15TiB

                 Metadata,single: Size:12.00GiB, Used:6.45GiB (53.75%)
                    /dev/sdb       12.00GiB

                 System,single: Size:32.00MiB, Used:144.00KiB (0.44%)
                    /dev/sdb       32.00MiB

                 Unallocated:
                    /dev/sdb      669.99GiB

              _Data_ is block group type, _single_ is block group profile, _Size_ is total  size  occupied
              by  this type, _Used_ is the actually used space, the percent is ratio of _Used/Size_. The
              _Unallocated_ is remaining space.

              **Options**

              **-b|--raw**
                     raw numbers in bytes, without the _B_ suffix

              **-h|--human-readable**
                     print human friendly numbers, base 1024, this is the default

              **-H     **print human friendly numbers, base 1000

              **--iec  **select the 1024 base for the following options, according to the IEC standard

              **--si   **select the 1000 base for the following options, according to the SI standard

              **-k|--kbytes**
                     show sizes in KiB, or kB with --si

              **-m|--mbytes**
                     show sizes in MiB, or MB with --si

              **-g|--gbytes**
                     show sizes in GiB, or GB with --si

              **-t|--tbytes**
                     show sizes in TiB, or TB with --si

              **-T     **show data in tabular format

              If conflicting options are passed, the last one takes precedence.

## EXAMPLES
### $ btrfs filesystem defrag -v -r dir/

       Recursively defragment files under **dir/**, print files as they are processed.  The  file  names
       will be printed in batches, similarly the amount of data triggered by defragmentation will be
       proportional  to  last N printed files. The system dirty memory throttling will slow down the
       defragmentation but there can still be a lot of IO load and the system may stall  for  a  mo‐
       ment.

### $ btrfs filesystem defrag -v -r -f dir/

       Recursively defragment files under **dir/**, be verbose and wait until all blocks are flushed be‐
       fore processing next file. You can note slower progress of the output and lower IO load (pro‐
       portional to currently defragmented file).

### $ btrfs filesystem defrag -v -r -f -clzo dir/

       Recursively  defragment  files  under **dir/**, be verbose, wait until all blocks are flushed and
       force file compression.

### $ btrfs filesystem defrag -v -r -t 64M dir/

       Recursively defragment files under **dir/**, be verbose and try to  merge  extents  to  be  about
       64MiB.  As  stated above, the success rate depends on actual free space fragmentation and the
       final result is not guaranteed to meet the target even if run repeatedly.

### $ btrfs filesystem resize -1G /path

### $ btrfs filesystem resize 1:-1G /path

       Shrink size of the filesystem's device id 1 by 1GiB. The first syntax expects a  device  with
       id  1 to exist, otherwise fails. The second is equivalent and more explicit. For a single-de‐
       vice filesystem it's typically not necessary to specify the devid though.

### $ btrfs filesystem resize max /path

### $ btrfs filesystem resize 1:max /path

       Let's assume that devid 1 exists and the filesystem does not occupy the whole  block  device,
       e.g.  it has been enlarged and we want to grow the filesystem. By simply using _max_ as size we
       will achieve that.

### NOTE:
          There are two ways to minimize the filesystem on a given device. The **btrfs  inspect-inter‐**
          **nal min-dev-size **command, or iteratively shrink in steps.

## EXIT STATUS
       **btrfs  filesystem  **returns a zero exit status if it succeeds. Non zero is returned in case of
       failure.

## AVAILABILITY
       **btrfs   **is   part   of   btrfs-progs.     Please    refer    to    the    documentation    at
       _<https://btrfs.readthedocs.io_>.

## SEE ALSO
       [_btrfs-subvolume(8)](https://www.chedong.com/phpMan.php/man/btrfs-subvolume/8/markdown)_, [_mkfs.btrfs(8)](https://www.chedong.com/phpMan.php/man/mkfs.btrfs/8/markdown)_


6.6.3                                       Mar 31, 2024                         [_BTRFS-FILESYSTEM_(8)](https://www.chedong.com/phpMan.php/man/BTRFS-FILESYSTEM/8/markdown)