<\/i><\/p>\nShow 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.<\/p>\n
An example with description:<\/p>\n
\u2022 device size: 1.9TiB<\/i>, one device, no RAID<\/p>\n
\u2022 filesystem size: 1.9TiB<\/i><\/p>\n
\u2022 created with: mkfs.btrfs \u2212d single \u2212m single<\/i><\/p>\n
$ 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<\/p>\n
\u2022 Data<\/i>, System<\/i> and Metadata<\/i> are separate block group types. GlobalReserve<\/i> is an artificial and internal emergency space, see below.<\/p>\n
\u2022 single<\/i> \u2014 the allocation profile, defined at mkfs time<\/p>\n
\u2022 total<\/i> \u2014 sum of space reserved for all allocation profiles of the given type, ie. all Data\/single. Note that it\u2019s not total size of filesystem.<\/p>\n
\u2022 used<\/i> \u2014 sum of used space of the above, ie. file extents, metadata blocks<\/p>\n
GlobalReserve<\/i> is an artificial and internal emergency space. It is used eg. when the filesystem is full. Its total<\/i> size is dynamic based on the filesystem size, usually not larger than 512MiB, used<\/i> may fluctuate.<\/p>\n
The GlobalReserve is a portion of Metadata. In case the filesystem metadata is exhausted, GlobalReserve\/total + Metadata\/used = Metadata\/total<\/i>. Otherwise there appears to be some unused space of Metadata.<\/p>\n
Options<\/b><\/p>\n
\u2212b|\u2212\u2212raw<\/p>\n
raw numbers in bytes, without the B<\/i> suffix<\/p>\n
\u2212h|\u2212\u2212human\u2212readable<\/p>\n
print human friendly numbers, base 1024, this is the default<\/p>\n
\u2212H<\/p>\n
print human friendly numbers, base 1000<\/p>\n
\u2212\u2212iec<\/p>\n
select the 1024 base for the following options, according to the IEC standard<\/p>\n
\u2212\u2212si<\/p>\n
select the 1000 base for the following options, according to the SI standard<\/p>\n
\u2212k|\u2212\u2212kbytes<\/p>\n
show sizes in KiB, or kB with \u2212\u2212si<\/p>\n
\u2212m|\u2212\u2212mbytes<\/p>\n
show sizes in MiB, or MB with \u2212\u2212si<\/p>\n
\u2212g|\u2212\u2212gbytes<\/p>\n
show sizes in GiB, or GB with \u2212\u2212si<\/p>\n
\u2212t|\u2212\u2212tbytes<\/p>\n
show sizes in TiB, or TB with \u2212\u2212si<\/p>\n
If conflicting options are passed, the last one takes precedence.<\/p>\n
defragment<\/b> [options] <\/i>|<\/i> [<\/i>|<\/i>…]<\/p>\nDefragment file data on a mounted filesystem. Requires kernel 2.6.33 and newer.<\/p>\n
If \u2212r<\/i> is passed, files in dir will be defragmented recursively (not descending to subvolumes, mount points and directory symlinks). The start position and the number of bytes to defragment can be specified by start and length using \u2212s<\/i> and \u2212l<\/i> options below. Extents bigger than value given by \u2212t<\/i> 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.<\/p>\n
Warning<\/big><\/b>
Defragmenting with Linux kernel versions < 3.9 or \u2265 3.14\u2212rc2 as well as with Linux stable kernel versions \u2265 3.10.31, \u2265 3.12.12 or \u2265 3.13.4 will break up the reflinks of COW data (for example files copied with cp \u2212\u2212reflink<\/b>, snapshots or de\u2212duplicated data). This may cause considerable increase of space usage depending on the broken up reflinks.<\/p>\n
Note<\/big><\/b>
Directory arguments without \u2212r<\/i> 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.<\/p>\n
For start<\/i>, len<\/i>, size<\/i> 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).<\/p>\n
Options<\/b><\/p>\n
\u2212c[<\/i>]<\/big><\/p>\ncompress file contents while defragmenting. Optional argument selects the compression algorithm, zlib<\/i> (default), lzo<\/i> or zstd<\/i>. Currently it\u2019s not possible to select no compression. See also section EXAMPLES<\/i>.<\/big><\/p>\n
\u2212r<\/big><\/p>\n
defragment files recursively in given directories, does not descend to subvolumes or mount points<\/big><\/p>\n
\u2212f<\/big><\/p>\n
flush data for each file before going to the next file.<\/big><\/p>\n
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\u2019s too much dirty data to write and it\u2019s not possible to make the reservations for the new data (ie. how the COW design works).<\/big><\/p>\n
\u2212s <\/i>[kKmMgGtTpPeE]<\/big><\/p>\ndefragmentation will start from the given offset, default is beginning of a file<\/big><\/p>\n
\u2212l <\/i>[kKmMgGtTpPeE]<\/big><\/p>\ndefragment only up to len<\/i> bytes, default is the file size<\/big><\/p>\n
\u2212t <\/i>[kKmMgGtTpPeE]<\/big><\/p>\ntarget extent size, do not touch extents bigger than size<\/i>, default: 32M<\/big><\/p>\n
The value is only advisory and the final size of the extents may differ, depending on the state of the free space and fragmentation or other internal logic. Reasonable values are from tens to hundreds of megabytes.<\/big><\/p>\n
\u2212v<\/big><\/p>\n
(deprecated) alias for global \u2212v<\/i> option<\/big><\/p>\n
du<\/b> [options] <\/i> [<\/i>..]<\/big><\/p>\nCalculate 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<\/i> value which is described below.<\/big><\/p>\n
Each argument to btrfs filesystem du<\/i> will have a set shared<\/i> value calculated for it. We define each set<\/i> as those files found by a recursive search of an argument (recursion descends to subvolumes but not mount points). The set shared<\/i> value then is a sum of all shared space referenced by the set.<\/big><\/p>\n
set shared<\/i> takes into account overlapping shared extents, hence it isn\u2019t as simple as adding up shared extents.<\/big><\/p>\n
Options<\/b><\/big><\/p>\n
\u2212s|\u2212\u2212summarize<\/big><\/p>\n
display only a total for each argument<\/big><\/p>\n
\u2212\u2212raw<\/big><\/p>\n
raw numbers in bytes, without the B<\/i> suffix.<\/big><\/p>\n
\u2212\u2212human\u2212readable<\/big><\/p>\n
print human friendly numbers, base 1024, this is the default<\/big><\/p>\n
\u2212\u2212iec<\/big><\/p>\n
select the 1024 base for the following options, according to the IEC standard.<\/big><\/p>\n
\u2212\u2212si<\/big><\/p>\n
select the 1000 base for the following options, according to the SI standard.<\/big><\/p>\n
\u2212\u2212kbytes<\/big><\/p>\n
show sizes in KiB, or kB with \u2212\u2212si.<\/big><\/p>\n
\u2212\u2212mbytes<\/big><\/p>\n
show sizes in MiB, or MB with \u2212\u2212si.<\/big><\/p>\n
\u2212\u2212gbytes<\/big><\/p>\n
show sizes in GiB, or GB with \u2212\u2212si.<\/big><\/p>\n
\u2212\u2212tbytes<\/big><\/p>\n
show sizes in TiB, or TB with \u2212\u2212si.<\/big><\/p>\n
label<\/b> [<\/i>|<\/i>] [<\/i>]<\/big><\/p>\nShow or update the label of a filesystem. This works on a mounted filesystem or a filesystem image.<\/big><\/p>\n
The newlabel<\/i> argument is optional. Current label is printed if the argument is omitted.<\/big><\/p>\n
Note<\/big><\/b>
the maximum allowable length shall be less than 256 chars and must not contain a newline. The trailing newline is stripped automatically.<\/big><\/p>\n
resize<\/big><\/b> [options] [<\/i>:][+\/\u2212]<\/i>[kKmMgGtTpPeE]|[<\/i>:]max <\/i><\/big><\/big><\/p>\nResize a mounted filesystem identified by path<\/i>. A particular device can be resized by specifying a devid<\/i>.<\/big><\/big><\/p>\n
Warning<\/big><\/b>
If path<\/i> 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.<\/big><\/big><\/p>\n
The devid<\/i> can be found in the output of btrfs filesystem show<\/b> and defaults to 1 if not specified. The size<\/i> parameter specifies the new size of the filesystem. If the prefix +<\/i> or \u2212<\/i> is present the size is increased or decreased by the quantity size<\/i>. If no units are specified, bytes are assumed for size<\/i>. Optionally, the size parameter may be suffixed by one of the following unit designators: ‘K’, ‘M’, ‘G’, ‘T’, ‘P’, or ‘E’, which represent KiB, MiB, GiB, TiB, PiB, or EiB, respectively (case does not matter).<\/big><\/big><\/p>\n
If max<\/i> is passed, the filesystem will occupy all available space on the device respecting devid<\/i> (remember, devid 1 by default).<\/big><\/big><\/p>\n
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<\/b>(8) or parted<\/b>(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.<\/big><\/big><\/p>\n
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\u2019s beyond the new end. Relocation of the data takes time.<\/big><\/big><\/p>\n
See also section EXAMPLES<\/i>.<\/big><\/big><\/p>\n
Options<\/b><\/big><\/big><\/p>\n
\u2212\u2212enqueue<\/big><\/big><\/big><\/p>\n
wait if there\u2019s another exclusive operation running, otherwise continue<\/big><\/big><\/big><\/p>\n
show<\/b> [options] [<\/i>|<\/i>|<\/i>|