{ "content": [ { "type": "text", "text": "# BTRFS-QGROUP (info)\n\n## NAME\n\nbtrfs-qgroup - control the quota group of a btrfs filesystem\n\n## SYNOPSIS\n\nbtrfs qgroup \n\n## DESCRIPTION\n\nbtrfs qgroup is used to control quota group (qgroup) of a btrfs\nfilesystem.\n\n## Sections\n\n- **NAME**\n- **SYNOPSIS**\n- **DESCRIPTION**\n- **QGROUP**\n- **SUBCOMMAND**\n- **QUOTA RESCAN**\n- **EXAMPLES**\n- **EXIT STATUS**\n- **AVAILABILITY**\n- **SEE ALSO**\n\nUse structuredContent.sections for detailed options, examples, and full documentation.\n" } ], "structuredContent": { "command": "BTRFS-QGROUP", "section": "", "mode": "info", "summary": "btrfs-qgroup - control the quota group of a btrfs filesystem", "synopsis": "btrfs qgroup ", "tldr_summary": null, "tldr_examples": [], "tldr_source": null, "flags": [], "examples": [ "Example 1. Make a parent group that has two quota group children", "Given the following filesystem mounted at /mnt/my-vault", "Label: none uuid: 60d2ab3b-941a-4f22-8d1a-315f329797b2", "Total devices 1 FS bytes used 128.00KiB", "devid 1 size 5.00GiB used 536.00MiB path /dev/vdb", "Enable quota and create subvolumes. Check subvolume ids.", "$ cd /mnt/my-vault", "$ btrfs quota enable .", "$ btrfs subvolume create a", "$ btrfs subvolume create b", "$ btrfs subvolume list .", "ID 261 gen 61 top level 5 path a", "ID 262 gen 62 top level 5 path b", "Create qgroup and set limit to 10MiB.", "$ btrfs qgroup create 1/100 .", "$ btrfs qgroup limit 10M 1/100 .", "$ btrfs qgroup assign 0/261 1/100 .", "$ btrfs qgroup assign 0/262 1/100 .", "And check qgroups.", "$ btrfs qgroup show .", "qgroupid rfer excl", "-------- ---- ----", "0/5 16.00KiB 16.00KiB", "0/261 16.00KiB 16.00KiB", "0/262 16.00KiB 16.00KiB", "1/100 32.00KiB 32.00KiB" ], "see_also": [ { "name": "mkfs.btrfs", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/mkfs.btrfs/8/json" }, { "name": "btrfs-subvolume", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/btrfs-subvolume/8/json" }, { "name": "btrfs-quota", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/btrfs-quota/8/json" } ], "section_outline": [ { "name": "NAME", "lines": 2, "subsections": [] }, { "name": "SYNOPSIS", "lines": 2, "subsections": [] }, { "name": "DESCRIPTION", "lines": 11, "subsections": [] }, { "name": "QGROUP", "lines": 21, "subsections": [] }, { "name": "SUBCOMMAND", "lines": 129, "subsections": [] }, { "name": "QUOTA RESCAN", "lines": 15, "subsections": [] }, { "name": "EXAMPLES", "lines": 37, "subsections": [] }, { "name": "EXIT STATUS", "lines": 3, "subsections": [] }, { "name": "AVAILABILITY", "lines": 3, "subsections": [] }, { "name": "SEE ALSO", "lines": 3, "subsections": [] } ], "sections": { "NAME": { "content": "btrfs-qgroup - control the quota group of a btrfs filesystem\n", "subsections": [] }, "SYNOPSIS": { "content": "btrfs qgroup \n", "subsections": [] }, "DESCRIPTION": { "content": "btrfs qgroup is used to control quota group (qgroup) of a btrfs\nfilesystem.\n\nNote\nTo use qgroup you need to enable quota first using btrfs quota\nenable command.\n\nWarning\nQgroup is not stable yet and will impact performance in current\nmainline kernel (v4.14).\n", "subsections": [] }, "QGROUP": { "content": "Quota groups or qgroup in btrfs make a tree hierarchy, the leaf qgroups\nare attached to subvolumes. The size limits are set per qgroup and\napply when any limit is reached in tree that contains a given\nsubvolume.\n\nThe limits are separated between shared and exclusive and reflect the\nextent ownership. For example a fresh snapshot shares almost all the\nblocks with the original subvolume, new writes to either subvolume will\nraise towards the exclusive limit.\n\nThe qgroup identifiers conform to level/id where level 0 is reserved to\nthe qgroups associated with subvolumes. Such qgroups are created\nautomatically.\n\nThe qgroup hierarchy is built by commands create and assign.\n\nNote\nIf the qgroup of a subvolume is destroyed, quota about the\nsubvolume will not be functional until qgroup 0/ is\ncreated again.\n", "subsections": [] }, "SUBCOMMAND": { "content": "assign [options] \nAssign qgroup as the child qgroup of in the btrfs\nfilesystem identified by .\n\nOptions\n\n--rescan\n(default since: 4.19) Automatically schedule quota rescan if\nthe new qgroup assignment would lead to quota inconsistency.\nSee QUOTA RESCAN for more information.\n\n--no-rescan\nExplicitly ask not to do a rescan, even if the assignment will\nmake the quotas inconsistent. This may be useful for repeated\ncalls where the rescan would add unnecessary overhead.\n\ncreate \nCreate a subvolume quota group.\n\nFor the 0/ qgroup, a qgroup can be created even\nbefore the subvolume is created.\n\ndestroy \nDestroy a qgroup.\n\nIf a qgroup is not isolated, meaning it is a parent or child\nqgroup, then it can only be destroyed after the relationship is\nremoved.\n\nlimit [options] |none [] \nLimit the size of a qgroup to or no limit in the btrfs\nfilesystem identified by .\n\nIf is not given, qgroup of the subvolume identified by\n is used if possible.\n\nOptions\n\n-c\nlimit amount of data after compression. This is the default, it\nis currently not possible to turn off this option.\n\n-e\nlimit space exclusively assigned to this qgroup.\n\nremove \nRemove the relationship between child qgroup and parent\nqgroup in the btrfs filesystem identified by .\n\nOptions\n\n--rescan\n(default since: 4.19) Automatically schedule quota rescan if\nthe removed qgroup relation would lead to quota inconsistency.\nSee QUOTA RESCAN for more information.\n\n--no-rescan\nExplicitly ask not to do a rescan, even if the removal will\nmake the quotas inconsistent. This may be useful for repeated\ncalls where the rescan would add unnecessary overhead.\n\nshow [options] \nShow all qgroups in the btrfs filesystem identified by .\n\nOptions\n\n-p\nprint parent qgroup id.\n\n-c\nprint child qgroup id.\n\n-r\nprint limit of referenced size of qgroup.\n\n-e\nprint limit of exclusive size of qgroup.\n\n-F\nlist all qgroups which impact the given path(include ancestral\nqgroups)\n\n-f\nlist all qgroups which impact the given path(exclude ancestral\nqgroups)\n\n--raw\nraw numbers in bytes, without the B suffix.\n\n--human-readable\nprint human friendly numbers, base 1024, this is the default\n\n--iec\nselect the 1024 base for the following options, according to\nthe IEC standard.\n\n--si\nselect the 1000 base for the following options, according to\nthe SI standard.\n\n--kbytes\nshow sizes in KiB, or kB with --si.\n\n--mbytes\nshow sizes in MiB, or MB with --si.\n\n--gbytes\nshow sizes in GiB, or GB with --si.\n\n--tbytes\nshow sizes in TiB, or TB with --si.\n\n--sort=[+/-][,[+/-]]...\nlist qgroups in order of .\n\n can be one or more of\nqgroupid,rfer,excl,maxrfer,maxexcl.\n\nPrefix '+' means ascending order and '-' means descending order\nof . If no prefix is given, use ascending order by\ndefault.\n\nIf multiple s is given, use comma to separate.\n\n--sync\nTo retrieve information after updating the state of qgroups,\nforce sync of the filesystem identified by before\ngetting information.\n", "subsections": [] }, "QUOTA RESCAN": { "content": "The rescan reads all extent sharing metadata and updates the respective\nqgoups accordingly.\n\nThe information consists of bytes owned exclusively (excl) or\nshared/referred to (rfer). There's no explicit information about which\nextents are shared or owned exclusively. This means when qgroup\nrelationship changes, extent owners change and qgroup numbers are no\nlonger consistent unless we do a full rescan.\n\nHowever there are cases where we can avoid a full rescan, if a\nsubvolume whose rfer number equals its excl number, which means all\nbytes are exclusively owned, then assigning/removing this subvolume\nonly needs to add/subtract rfer number from its parent qgroup. This can\nspeed up the rescan.\n", "subsections": [] }, "EXAMPLES": { "content": "Example 1. Make a parent group that has two quota group children\n\nGiven the following filesystem mounted at /mnt/my-vault\n\nLabel: none uuid: 60d2ab3b-941a-4f22-8d1a-315f329797b2\nTotal devices 1 FS bytes used 128.00KiB\ndevid 1 size 5.00GiB used 536.00MiB path /dev/vdb\n\nEnable quota and create subvolumes. Check subvolume ids.\n\n$ cd /mnt/my-vault\n$ btrfs quota enable .\n$ btrfs subvolume create a\n$ btrfs subvolume create b\n$ btrfs subvolume list .\n\nID 261 gen 61 top level 5 path a\nID 262 gen 62 top level 5 path b\n\nCreate qgroup and set limit to 10MiB.\n\n$ btrfs qgroup create 1/100 .\n$ btrfs qgroup limit 10M 1/100 .\n$ btrfs qgroup assign 0/261 1/100 .\n$ btrfs qgroup assign 0/262 1/100 .\n\nAnd check qgroups.\n\n$ btrfs qgroup show .\n\nqgroupid rfer excl\n-------- ---- ----\n0/5 16.00KiB 16.00KiB\n0/261 16.00KiB 16.00KiB\n0/262 16.00KiB 16.00KiB\n1/100 32.00KiB 32.00KiB\n", "subsections": [] }, "EXIT STATUS": { "content": "btrfs qgroup returns a zero exit status if it succeeds. Non zero is\nreturned in case of failure.\n", "subsections": [] }, "AVAILABILITY": { "content": "btrfs is part of btrfs-progs. Please refer to the btrfs wiki\nhttp://btrfs.wiki.kernel.org for further details.\n", "subsections": [] }, "SEE ALSO": { "content": "mkfs.btrfs(8), btrfs-subvolume(8), btrfs-quota(8),\n\nBtrfs v5.16.2 02/16/2022 BTRFS-QGROUP(8)", "subsections": [] } } } }