btrfs man page on Oracle

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BTRFS(8)			     btrfs			      BTRFS(8)

       btrfs - control a btrfs filesystem

       btrfs subvolume create [-i <qgroupid>] [<dest>/]<name>

       btrfs subvolume delete <subvolume> [<subvolume>...]

       btrfs   subvolume   list	 [options]  [-G	 [+|-]value]  [-C  [+|-]value]
       [--sort=rootid,gen,ogen,path] <path>

       btrfs subvolume snapshot [-r] <source> <dest>|[<dest>/]<name>

       btrfs subvolume get-default <path>

       btrfs subvolume set-default <id> <path>

       btrfs subvolume find-new <subvolume> <lastgen>

       btrfs subvolume show <path>

       btrfs filesystem df <path>

       btrfs filesystem show [--mounted|--all-devices|<uuid>]

       btrfs filesystem sync <path>

       btrfs filesystem defragment [options] <file>|<dir> [<file>|<dir>...]

       btrfs filesystem resize [devid:][+/-]<size>[gkm]|[devid:]max <path>

       btrfs filesystem label [<device>|<mount_point>] [<newlabel>]

       btrfs [filesystem] balance start [options] <path>

       btrfs [filesystem] balance pause <path>

       btrfs [filesystem] balance cancel <path>

       btrfs [filesystem] balance resume <path>

       btrfs [filesystem] balance status [-v] <path>

       btrfs device add [-Kf] <device> [<device>...] <path>

       btrfs device delete <device> [<device>...] <path>

       btrfs device scan [--all-devices|<device> P[<device>...]

       btrfs device ready <device>

       btrfs device stats [-z] {<path>|<device>}

       btrfs  scrub  start  [-BdqrR]  [-c  ioprio_class	 -n  ioprio_classdata]

       btrfs scrub cancel {<path>|<device>}

       btrfs  scrub  resume  [-BdqrR]  [-c  ioprio_class  -n ioprio_classdata]

       btrfs scrub status [-d] {<path>|<device>}

       btrfs check [options] <device>

       btrfs rescue chunk-recover [options] <path>

       btrfs rescue super-recover [options] <path>

       btrfs restore [options] <device>

       btrfs inspect-internal inode-resolve [-v] <inode> <path>

       btrfs inspect-internal  logical-resolve	[-Pv]  [-s  <size>]  <logical>

       btrfs inspect-internal subvolid-resolve <subvolid> <path>

       btrfs inspect-internal rootid <path>

       btrfs send [-v] [-p <parent>] [-c <clone-src>] [-f <outfile>] <subvol>

       btrfs receive [-ve] [-f <infile>] <mount>

       btrfs quota enable <path>

       btrfs quota disable <path>

       btrfs quota rescan [-s] <path>

       btrfs qgroup assign <src> <dst> <path>

       btrfs qgroup remove <src> <dst> <path>

       btrfs qgroup create <qgroupid> <path>

       btrfs qgroup destroy <qgroupid> <path>

       btrfs qgroup show <path>

       btrfs qgroup limit [options] <size>|none [<qgroupid>] <path>

       btrfs replace start [-Bfr] <srcdev>|<devid> <targetdev> <mount_point>

       btrfs replace status [-1] <mount_point>

       btrfs replace cancel <mount_point>

       btrfs help|--help

       btrfs <command> --help

       btrfs  is  used to control the filesystem and the files and directories
       stored. It is the tool to create or destroy a snapshot or  a  subvolume
       for  the filesystem, to defrag a file or a directory, flush the data to
       the disk, to resize the filesystem, to scan the device.

       It is possible to abbreviate  the  commands  unless  the	 commands  are
       ambiguous.   For example: it is possible to run btrfs sub snaps instead
       of btrfs subvolume snapshot.  But btrfs file s is not allowed,  because
       file  s	may  be	 interpreted both as filesystem show and as filesystem
       sync.  In this case btrfs returns filesystem sync If a command is  ter‐
       minated	by --help , the detailed help is showed. If the passed command
       matches more commands, detailed help of all  the	 matched  commands  is
       showed. For example btrfs dev --help shows the help of all device* com‐

       subvolume create [-i <qgroupid>] [<dest>/]<name>
	      Create a subvolume <name> in <dest>.  If	<dest>	is  not	 given
	      subvolume <name> will be created in the current directory.


	      -i <qgroupid>
		   Add	the  newly  created subvolume to a qgroup. This option
		   can be given multiple times.

       subvolume delete <subvolume> [<subvolume>...]
	      Delete the subvolume <subvolume>. If <subvolume> is not  a  sub‐
	      volume, btrfs returns an error.

       subvolume    list    [options]	 [-G   [+|-]value]   [-C   [+|-]value]
       [--sort=rootid,gen,ogen,path] <path>

	      List the subvolumes present in the filesystem <path>. For	 every
	      subvolume	 the  following	 information  is shown by default.  ID
	      <ID> top level <ID> path <path> where path is the relative  path
	      of the subvolume to the top level subvolume.

	      The subvolume's ID may be used by the subvolume set-default com‐
	      mand, or at mount time via  the  subvolid=  option.   If	-p  is
	      given,  then  parent  <ID> is added to the output between ID and
	      top level. The parent's ID may be used at	 mount	time  via  the
	      subvolrootid= option.


	      -p   print parent ID.

	      -a   print  all the subvolumes in the filesystem and distinguish
		   between absolute and relative  path	with  respect  to  the
		   given <path>.

	      -c   print  the  ogeneration  of the subvolume, aliases: ogen or
		   origin generation.

	      -g   print the generation of the subvolume.

	      -o   print only subvolumes bellow specified <path>.

	      -u   print the UUID of the subvolume.

	      -q   print the parent uuid of subvolumes (and snapshots).

	      -t   print the result as a table.

	      -s   only snapshot subvolumes in the filesystem will be listed.

	      -r   only readonly subvolumes in the filesystem will be listed.

	      -G [+|-]value
		   list subvolumes in the filesystem that  its	generation  is
		   >=,	<= or = value. '+' means >= value, '-' means <= value,
		   If there is neither '+' nor '-', it means = value.

	      -C [+|-]value
		   list subvolumes in the filesystem that its  ogeneration  is
		   >=, <= or = value. The usage is the same to '-g' option.

		   list	 subvolumes  in order by specified items.  you can add
		   '+' or '-' in front of each items, '+' means ascending, '-'
		   means descending. The default is ascending.

		   for --sort you can combine some items together by ',', just
		   like -sort=+ogen,-gen,path,rootid.

       subvolume snapshot [-r] <source> <dest>|[<dest>/]<name>
	      Create a writable/readonly snapshot of  the  subvolume  <source>
	      with the name <name> in the <dest> directory.  If only <dest> is
	      given, the subvolume will be named the basename of <source>.  If
	      <source>	is  not a subvolume, btrfs returns an error.  If -r is
	      given, the snapshot will be readonly.

       subvolume get-default <path>
	      Get the default subvolume of the filesystem <path>.  The	output
	      format is similar to subvolume list command.

       subvolume set-default <id> <path>
	      Set  the	subvolume of the filesystem <path> which is mounted as
	      default. The subvolume is identified by <id>, which is  returned
	      by the subvolume list command.

       subvolume find-new <subvolume> <last_gen>
	      List   the   recently  modified  files  in  a  subvolume,	 after
	      <last_gen> ID.

       subvolume show <path>
	      Show information of a given subvolume in the <path>.

       filesystem df <path>
	      Show space usage information for a mount point.

       filesystem show [--mounted|--all-devices|<uuid>]
	      Show the btrfs filesystem	 with  some  additional	 info.	If  no
	      option  or  UUID	is  passed, btrfs shows information of all the
	      btrfs filesystem both mounted and unmounted.   If	 --mounted  is
	      passed,  it  would  probe	 btrfs	kernel	to  list mounted btrfs
	      filesystem(s); If --all-devices is passed, all the devices under
	      /dev  are	 scanned; otherwise the devices list is extracted from
	      the /proc/partitions file.

       filesystem sync <path>
	      Force a sync for the filesystem identified by <path>.

       filesystem defragment [options] <file>|<dir> [<file>|<dir>...]
	      Defragment file data and/or directory metadata. If -r is passed,
	      files in dir will be defragmented recursively.

	      The  start position and the number of bytes to defragment can be
	      specified by start and len. Any  extent  bigger  than  threshold
	      will  be	considered already defragged. Use 0 to take the kernel
	      default, and use 1 to say every single extent must be rewritten.
	      You can also turn on compression in defragment operations.


	      -v   be verbose

	      -c   compress file contents while defragmenting

	      -r   defragment files recursively

	      -f   flush filesystem after defragmenting

	      -s start
		   defragment only from byte start onward

	      -l len
		   defragment only up to len bytes

	      -t size
		   defragment only files at least size bytes big

		   For start, len, size it is possible to append a suffix like
		   k for 1 KBytes, m for 1 MBytes...

		   NOTE: defragmenting with kernels up to 2.6.37  will	unlink
		   COW-ed  copies  of data, don't use it if you use snapshots,
		   have	 de-duplicated	your  data  or	made  copies  with  cp

       filesystem resize [devid:][+/-]<size>[gkm]|[devid:]max <path>
	      Resize  a	 filesystem  identified	 by  <path> for the underlying
	      device devid.  The devid can be found with btrfs filesystem show
	      and defaults to 1 if not specified.  The <size> parameter speci‐
	      fies the new size of the filesystem.  If the prefix +  or	 -  is
	      present  the  size  is  increased	 or  decreased by the quantity
	      <size>.  If no units are	specified,  the	 unit  of  the	<size>
	      parameter	 defaults to bytes. Optionally, the size parameter may
	      be suffixed by one of the following units designators: 'K', 'M',
	      or 'G', kilobytes, megabytes, or gigabytes, respectively.

	      If  'max'	 is  passed,  the filesystem will occupy all available
	      space on the device devid.

	      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)  or	 parted(8)  to
	      delete  the  existing  partition	and  recreate  it with the new
	      desired size.  When recreating the partition make	 sure  to  use
	      the same starting disk cylinder as before.

       filesystem label [<dev>|<mount_point>] [newlabel]
	      Show  or	update	the  label  of a filesystem. [<device>|<mount‐
	      point>] is used to  identify  the	 filesystem.   If  a  newlabel
	      optional argument is passed, the label is changed. The following
	      constraints exist for a label:

	      - the maximum allowable length shall be less than 256 chars

       [filesystem] balance start [options] <path>
	      Balance chunks across the devices Balance and/or convert (change
	      allocation  profile  of)	chunks	that  passed  all filters in a
	      comma-separated list of filters for a particular chunk type.  If
	      filter  list  is	not given balance all chunks of that type.  In
	      case none of the -d, -m or  -s  options  is  given  balance  all
	      chunks in a filesystem.


		   act on data chunks

		   act on metadata chunks

		   act on system chunks (only under -f)

	      -v   be verbose

	      -f   force reducing of metadata integrity

       [filesystem] balance pause <path>
	      Pause running balance.

       [filesystem] balance cancel <path>
	      Cancel running or paused balance.

       [filesystem] balance resume <path>
	      Resume interrupted balance.

       [filesystem] balance status [-v] <path>
	      Show status of running or paused balance.


	      -v   be verbose

       device add [-Kf] <dev> [<dev>...] <path>
	      Add device(s) to the filesystem identified by <path>.  If appli‐
	      cable, a whole device discard (TRIM) operation is performed.


		   do not perform discard by default

		   force overwrite of existing filesystem on the given disk(s)

       device delete <dev> [<dev>...] <path>
	      Remove device(s) from a filesystem identified by <path>.

       device scan [--all-devices|<device> [<device>...]
	      If one or more devices are passed, these are scanned for a btrfs
	      filesystem.   If no devices are passed, btrfs uses block devices
	      containing btrfs filesystem as listed  by	 blkid.	  Finally,  if
	      --all-devices is passed, all the devices under /dev are scanned.

       device ready <device>
	      Check  device  to see if it has all of it's devices in cache for

       device stats [-z] {<path>|<device>}
	      Read and print the device	 IO  stats  for	 all  devices  of  the
	      filesystem identified by <path> or for a single <device>.


	      -z   Reset stats to zero after reading them.

       scrub	start	[-BdqrR]   [-c	 ioprio_class	-n   ioprio_classdata]
	      Start a scrub on all devices of  the  filesystem	identified  by
	      <path>  or  on  a	 single	 <device>.  Without  options, scrub is
	      started as a background process. Progress can be	obtained  with
	      the  scrub  status  command. Scrubbing involves reading all data
	      from all disks and verifying  checksums.	Errors	are  corrected
	      along the way if possible.

	      The default IO priority of scrub is the idle class. The priority
	      can be configured similar to the ionice(1) syntax.


	      -B   Do not background and print scrub statistics when finished.

	      -d   Print separate statistics for each device of the filesystem
		   (-B only).

	      -q   Quiet. Omit error messages and statistics.

	      -r   Read only mode. Do not attempt to correct anything.

	      -R   Raw print mode. Print full data instead of summary.

	      -c ioprio_class
		   Set IO priority class (see ionice(1) manpage).

	      -n ioprio_classdata
		   Set IO priority classdata (see ionice(1) manpage).

       scrub cancel {<path>|<device>}
	      If  a  scrub  is running on the filesystem identified by <path>,
	      cancel it.  Progress is saved in the  scrub  progress  file  and
	      scrubbing	 can  be resumed later using the scrub resume command.
	      If a <device> is given, the corresponding	 filesystem  is	 found
	      and scrub cancel behaves as if it was called on that filesystem.

       scrub   resume	[-BdqrR]   [-c	 ioprio_class	-n   ioprio_classdata]
	      Resume a canceled or interrupted scrub cycle on  the  filesystem
	      identified  by  <path>  or on a given <device>. Does not start a
	      new scrub if the last scrub finished successfully.


	      see scrub start.

       scrub status [-d] {<path>|<device>}
	      Show status of a running scrub for the filesystem identified  by
	      <path>  or  for the specified <device>.  If no scrub is running,
	      show statistics of the last finished or canceled scrub for  that
	      filesystem or device.


	      -d   Print  separate  statistics for each device of the filesys‐

       check [options] <device>
	      Check an unmounted btrfs filesystem.


	      -s|--support <superblock>
		   use this superblock copy.

		   try to repair the filesystem.

		   create a new CRC tree.

		   create a new extent tree.

       rescue chunk-recover [options] <device>
	      Recover the chunk tree by scanning the devices one by one.


	      -y   assume an answer of 'yes' to all questions.

	      -v   verbose mode.

	      -h   help.

       rescue super-recover [options] <device>
	      Recover bad superblocks from good copies.


	      -y   assume an answer of 'yes' to all questions.

	      -v   verbose mode.

       restore [options] <device>
	      Try to restore files from a damaged filesystem(unmounted).


	      -s   get snapshots.

	      -x   get extended attributes.

	      -v   verbose.

	      -i   ignore errors.

	      -o   overwrite.

	      -t <location>
		   tree location.

	      -f <offset>
		   filesystem location.

	      -u <block>
		   super mirror.

	      -r <rootid>
		   root objectid.

	      -d   find dir.

	      -l   list tree roots.

       inspect-internal inode-resolve [-v] <inode> <path>
	      Resolves an <inode> in subvolume <path> to all filesystem paths.


	      -v   verbose mode. print count of	 returned  paths  and  ioctl()
		   return value

       inspect-internal logical-resolve [-Pv] [-s bufsize] <logical> <path>
	      Resolves a <logical> address in the filesystem mounted at <path>
	      to all inodes.  By default, each inode is	 then  resolved	 to  a
	      file system path (similar to the inode-resolve subcommand).


	      -P   skip the path resolving and print the inodes instead

	      -v   verbose mode. print count of returned paths and all ioctl()
		   return values

	      -s <bufsize>
		   set inode container's size. This is used to increase	 inode
		   container's	size  in case it is not enough to read all the
		   resolved results. The max value one can set is 64k.

       inspect-internal subvolid-resolve <subvolid> <path>
	      Get file system paths for the given subvolume ID.

       inspect-internal rootid <path>
	      For a given file or directory, return the containing  tree  root
	      id. For a subvolume return it's own tree id.

	      The  result  is  undefined  for  the  so-called empty subvolumes
	      (identified by inode number 2).

       send [-v] [-p <parent>] [-c <clone-src>] [-f <outfile>] <subvol>
	      Send the subvolume to stdout.  Sends the subvolume specified  by
	      <subvol>	to  stdout.  By default, this will send the whole sub‐
	      volume. To do an incremental send, use  '-p  <parent>'.  If  you
	      want  to	allow  btrfs  to clone from any additional local snap‐
	      shots, use '-c <clone-src>' (multiple times  where  applicable).
	      You  must	 not  specify  clone sources unless you guarantee that
	      these snapshots are exactly in the same state on both sides, the
	      sender  and  the	receiver. It is allowed to omit the which case
	      'btrfs send' will determine a suitable parent  among  the	 clone
	      sources itself.


	      -v   Enable verbose debug output. Each occurrence of this option
		   increases the verbose level more.

	      -p <parent>
		   Send an incremental stream from <parent> to <subvol>.

	      -c <clone-src>
		   Use this snapshot as a clone source for an incremental send
		   (multiple allowed).

	      -f <outfile>
		   Output  is  normally written to stdout. To write to a file,
		   use this option.  An alternative would be to use pipes.

       receive [-ve] [-f <infile>] <mount>
	      Receive subvolumes from stdin.  Receives one or more  subvolumes
	      that  were previously sent with btrfs send. The received subvol‐
	      umes are stored into <mount>.  btrfs receive will fail in case a
	      receiving	 subvolume already exists. It will also fail in case a
	      previously received subvolume was changed after it was received.
	      After receiving a subvolume, it is immediately set to read only.


	      -v   Enable verbose debug output. Each occurrence of this option
		   increases the verbose level more.

	      -f <infile>
		   By default, btrfs receive uses stdin to receive the subvol‐
		   umes.  Use this option to specify a file to use instead.

	      -e   Terminate  after receiving an <end cmd> in the data stream.
		   Without this option, the receiver  terminates  only	if  an
		   error is recognized or on EOF.

       quota enable <path>
	      Enable subvolume quota support for a filesystem.

       quota disable <path>
	      Disable subvolume quota support for a filesystem.

       quota rescan [-s] <path>
	      Trash  all  qgroup  numbers and scan the metadata again with the
	      current config.


	      -s   show status of a running rescan operation.

       qgroup assign <src> <dst> <path>
	      Enable subvolume qgroup support for a filesystem.

       qgroup remove <src> <dst> <path>
	      Remove a subvol from a quota group.

       qgroup create <qgroupid> <path>
	      Create a subvolume quota group.

       qgroup destroy <qgroupid> <path>
	      Destroy a subvolume quota group.

       qgroup show <path>
	      Show all subvolume quota groups.

       qgroup limit [options] <size>|none [<qgroupid>] <path>
	      Limit the size of a subvolume quota group.

       replace start [-Bfr] <srcdev>|<devid> <targetdev> <path>
	      Replace device of a btrfs filesystem.   On  a  live  filesystem,
	      duplicate	 the  data  to	the  target  device which is currently
	      stored on the source device. If the source device is not	avail‐
	      able anymore, or if the -r option is set, the data is built only
	      using the RAID redundancy mechanisms. After  completion  of  the
	      operation, the source device is removed from the filesystem.  If
	      the <srcdev> is a numerical value,  it  is  assumed  to  be  the
	      device  id  of  the  filesystem which is mounted at mount_point,
	      otherwise is is the path to the source  device.  If  the	source
	      device  is  disconnected,	 from  the system, you have to use the
	      devid parameter format.  The <targetdev> needs to be  same  size
	      or larger than the <srcdev>.


	      -r   only	 read  from  <srcdev>  if  no other zero-defect mirror
		   exists (enable this if your drive has lots of read  errors,
		   the access would be very slow)

	      -f   force  using	 and  overwriting <targetdev> even if it looks
		   like containing a valid btrfs filesystem. A valid  filesys‐
		   tem	is  assumed  if a btrfs superblock is found which con‐
		   tains a  correct  checksum.	Devices	 which	are  currently
		   mounted are never allowed to be used as the <targetdev>

	      -B   do not background

       replace status [-1] <mount_point>
	      Print  status  and  progress  information	 of  a	running device
	      replace operation.


	      -1   print once instead of print continuously until the  replace
		   operation finishes (or is canceled)

       replace cancel <mount_point>
	      Cancel a running device replace operation.

       btrfs  returns a zero exist status if it succeeds. Non zero is returned
       in case of failure.

       btrfs is part of btrfs-progs. Btrfs filesystem is currently under heavy
       development,  and not suitable for any uses other than benchmarking and
       review.	Please refer to the  btrfs  wiki
       for further details.

       mkfs.btrfs(8), ionice(1)

btrfs								      BTRFS(8)

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