Manpage/btrfs-qgroup

From btrfs Wiki
Jump to: navigation, search

Contents

btrfs-qgroup(8) manual page

Warning: this page is automatically generated from git, all edits will be lost. Current git version.


NAME

btrfs-qgroup - control the quota group of a btrfs filesystem

SYNOPSIS

btrfs qgroup <subcommand> <args>

DESCRIPTION

btrfs qgroup is used to control quota group (qgroup) of a btrfs filesystem.

Note: To use qgroup you need to enable quota first using btrfs quota enable command.
Warning: Qgroup is not stable yet and will impact performance in current mainline kernel (v3.14 so far).

QGROUP

Quota groups or qgroup in btrfs make a tree hierarchy, the leaf qgroups are attached to subvolumes. The size limits are set per qgroup and apply when any limit is reached in tree that contains a given subvolume.

The limits are separated between shared and exclusive and reflect the extent ownership. For example a fresh snapshot shares almost all the blocks with the original subvolume, new writes to either subvolume will raise towards the exclusive limit.

The qgroup identifiers conform to level/id where level 0 is reserved to the qgroups associated with subvolumes. Such qgroups are created automatically.

The qgroup hierarchy is built by commands create and assign.

Note: If the qgroup of a subvolume is destroyed, quota about the subvolume will not be functional until qgroup 0/<em><subvolume id></em> is created again.

SUBCOMMAND

assign [options] <src> <dst> <path>

Assign qgroup <src> as the child qgroup of <dst> in the btrfs filesystem identified by <path>.

Options

--rescan

Automatically schedule quota rescan if the new qgroup assignment leads to quota inconsistency.

--no-rescan

Explicitly ask not to do a rescan.

create <qgroupid> <path>

Create a subvolume quota group.

For the 0/<em><subvolume id></em> qgroup, a qgroup can be created even before the subvolume created.

destroy <qgroupid> <path>

Destroy a qgroup.

If a qgroup is no isolated,which means it is a parent or child qgroup, it can’t be destroyed.

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

Limit the size of a qgroup to <size> or no limit in the btrfs filesystem identified by <path>.

If <qgroupid> is not given, qgroup of the subvolume identified by <path> is used if possible.

Options

-c

limit amount of data after compression. This is the default, it is currently not possible to turn off this option.

-e

limit space exclusively assigned to this qgroup.

remove <src> <dst> <path>

Remove the relationship between child qgroup <src> and parent qgroup <dst> in the btrfs filesystem identified by <path>.

show [options] <path>

Show all qgroups in the btrfs filesystem identified by <path>.

Options

-p

print parent qgroup id.

-c

print child qgroup id.

-r

print limit of referenced size of qgroup.

-e

print limit of exclusive size of qgroup.

-F

list all qgroups which impact the given path(include ancestral qgroups)

-f

list all qgroups which impact the given path(exclude ancestral qgroups)

--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.

--sort=[+/-]<attr>[,[+/-]<attr>]…

list qgroups in order of <attr>.

<attr> can be one or more of qgroupid,rfer,excl,max_rfer,max_excl.

Prefix '+' means ascending order and '-' means descending order of <attr>. If no prefix is given, use ascending order by default.

If multiple <attr>s is given, use comma to separate.

--sync

To retrieve information after updating the state of qgroups, force sync of the filesystem identified by <path> before getting information.

EXIT STATUS

btrfs qgroup 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), btrfs-subvolume(8), btrfs-quota(8),

Personal tools