btrfs-qgroup(8) =============== NAME ---- btrfs-qgroup - control the quota group of a btrfs filesystem SYNOPSIS -------- *btrfs qgroup* 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 limit sare 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/' is created again. SUBCOMMAND ---------- *assign* [options] :: Assign qgroup as the child qgroup of in the btrfs filesystem identified by . + `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* :: Create a subvolume quota group. + For the '0/' qgroup, a qgroup can be created even before the subvolume created. *destroy* :: 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] |none [] :: Limit the size of a qgroup to or no limit in the btrfs filesystem identified by . + If is not given, qgroup of the subvolume identified by 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* :: Remove the relationship between child qgroup and parent qgroup in the btrfs filesystem identified by . *show* [options] :: Show all qgroups in the btrfs filesystem identified by . + `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=[\+/-][,[+/-]]...:::: list qgroups in order of . + can be one or more of qgroupid,rfer,excl,max_rfer,max_excl. + Prefix \'+' means ascending order and \'-' means descending order of . If no prefix is given, use ascending order by default. + If multiple s is given, use comma to separate. 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),