Provided by: btrfs-tools_4.4-1_i386 bug

NAME

       btrfs-filesystem - command group of btrfs that usually work on the
       whole filesystem

SYNOPSIS

       btrfs filesystem <subcommand> <args>

DESCRIPTION

       btrfs filesystem is used to do the whole filesystem level tasks,
       including all the regular filesystem operations like resizing, space
       stats, label setting/getting, and defragmentation.

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 separeate block group types.
               GlobalReserve is an artificial 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, ie. all Data/single. Note that it’s not total
               size of filesystem.

           ·   used — sum of used space of the above, ie. file extents,
               metadata blocks

           GlobalReserve is an artificial and internal emergency space. It is
           used eg. when the filesystem is full. Its total size is dynamic
           based on the filesystem size, usually not larger than 512MiB, used
           may fluctuate.

           The global block reserve is accounted within Metadata. In case the
           filesystem metadata are exhausted, GlobalReserve/total +
           Metadata/used = Metadata/total.

           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 filesytem.

           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 using -s and -l options below. 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 256kB 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 ref-links 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 ref-links.
           Options

           -v
               be verbose, print file names as they’re submitted for
               defragmentation

           -c[<algo>]
               compress file contents while defragmenting. Optional argument
               selects the compression algorithm, zlib (default) or lzo.
               Currently it’s not possible to select no compression. See also
               section EXAMPLES.

           -r
               defragment files recursively in given directories

           -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 cumulates from several files and may increase system
               load.

           -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

               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).

                   Note
                   Directory arguments without -r do not defragment files
                   recursively but will defragment certain internal trees
                   (extent tree and the subvolume tree). This has been
                   confusing and could be removed in the future.

       label [<dev>|<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
           the argument is omitted.

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

       resize [<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 prefix + 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 units
           designators: 'K', 'M', 'G', 'T', 'P', or 'E', which represent 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 respecting 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) 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
           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.

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

           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 manager (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. This is done via a special
           ioctl and will also trigger cleaning of deleted subvolumes. Besides
           that it’s equivalent to the sync(1) 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 fi 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
                   Used:                          1.14TiB
                   Free (estimated):            692.57GiB      (min: 692.57GiB)
                   Data ratio:                       1.00
                   Metadata ratio:                   1.00
                   Global reserve:              512.00MiB      (used: 0.00B)

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

               Data,single: Size:1.15TiB, Used:1.13TiB
                  /dev/sdb        1.15TiB

               Metadata,single: Size:12.00GiB, Used:6.45GiB
                  /dev/sdb       12.00GiB

               System,single: Size:32.00MiB, Used:144.00KiB
                  /dev/sdb       32.00MiB

               Unallocated:
                  /dev/sdb      669.99GiB

           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 moment.

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

       Recusively defragment files under dir/, be verbose and wait until all
       blocks are flushed before processing next file. You can note slower
       progress of the output and lower IO load (proportional to currently
       defragmented file).

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

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

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

       Recusively 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-device 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, the filesystem does not occupy the
       whole block device, eg. it has been enlarged and we wan the grow the
       filesystem. 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-internal 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 btrfs wiki
       http://btrfs.wiki.kernel.org for further details.

SEE ALSO

       mkfs.btrfs(8),