443 lines
17 KiB
Plaintext
443 lines
17 KiB
Plaintext
btrfs-filesystem(8)
|
|
===================
|
|
|
|
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 defragmentation. 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 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 GlobalReserve is a portion of Metadata. In case the filesystem metadata is
|
|
exhausted, '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 subvolumes, 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 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 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
|
|
defragment 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 compression
|
|
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
|
|
subvolumes 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 (ie. 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: 32M
|
|
+
|
|
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.
|
|
+
|
|
-v::::
|
|
(deprecated) alias for global '-v' option
|
|
|
|
*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 (recursion 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 omitted.
|
|
+
|
|
NOTE: the maximum allowable length shall be less than 256 chars and must not contain
|
|
a newline. The trailing newline is stripped automatically.
|
|
|
|
// Some wording are extracted by the resize2fs man page
|
|
*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 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
|
|
unit 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'.
|
|
+
|
|
`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
|
|
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', similar to the `sync`(1) command. In
|
|
addition, it starts cleaning of deleted subvolumes. To wait for the subvolume
|
|
deletion to complete 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
|
|
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
|
|
* '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 (difference of the above two numbers)
|
|
* 'Device missing' -- sum of capacity of all missing devices
|
|
* '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` 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 (eg.
|
|
multiple profiles).
|
|
* 'Data ratio' -- ratio of total space for data including redundancy or parity to
|
|
the effectively usable data space, eg. single is 1.0, RAID1 is 2.0 and for RAID5/6
|
|
it depends on the number of devices
|
|
* 'Metadata ratio' -- dtto, 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 profile (single, raid1, ...), see `btrfs`(5)
|
|
section 'FILESYSTEMS WITH MULTIPLE BLOCK GROUP 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 anymory, the chunks have to
|
|
be reclaimed and zones reset 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 moment.
|
|
|
|
*$ btrfs filesystem defrag -v -r -f dir/*
|
|
|
|
Recursively 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/*
|
|
|
|
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-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 and the filesystem does not occupy the whole
|
|
block device, eg. 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-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
|
|
--------
|
|
`btrfs-subvolume`(8),
|
|
`mkfs.btrfs`(8),
|