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NAME | SYNOPSIS | DESCRIPTION | QUOTA OVERVIEW | USER COMMANDS | QUOTA ADMINISTRATION | ADMINISTRATOR COMMANDS | DIRECTORY TREE QUOTA | EXAMPLES | CAVEATS | BUGS | FILES | SEE ALSO | COLOPHON |
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xfs_quota(8) System Manager's Manual xfs_quota(8)
xfs_quota - manage use of quota on XFS filesystems
xfs_quota [ -x ] [ -f ] [ -p prog ] [ -c cmd ] ... [ -d project ]
... [ -D projects_file ] [ -P projid_file ] [ path ... ]
xfs_quota -V
xfs_quota is a utility for reporting and editing various aspects
of filesystem quota.
The options to xfs_quota are:
-c cmd xfs_quota commands may be run interactively (the default)
or as arguments on the command line. Multiple -c arguments
may be given. The commands are run in the sequence given,
then the program exits.
-p prog
Set the program name for prompts and some error messages,
the default value is xfs_quota.
-x Enable expert mode. All of the administrative commands
(see the ADMINISTRATOR COMMANDS section below) which allow
modifications to the quota system are available only in
expert mode.
-f Enable foreign filesystem mode. A limited number of user
and administrative commands are available for use on some
foreign (non-XFS) filesystems.
-d project
Project names or numeric identifiers may be specified with
this option, which restricts the output of the individual
xfs_quota commands to the set of projects specified.
Multiple -d arguments may be given.
-D projects_file
Specify a file containing the mapping of numeric project
identifiers to directory trees. /etc/projects as default,
if this option is none.
-P projid_file
Specify a file containing the mapping of numeric project
identifiers to project names. /etc/projid as default, if
this option is none.
-V Prints the version number and exits.
The optional path argument(s) can be used to specify mount points
or device files which identify XFS filesystems. The output of the
individual xfs_quota commands will then be restricted to the set
of filesystems specified.
This manual page is divided into two sections - firstly,
information for users of filesystems with quota enabled, and the
xfs_quota commands of interest to such users; and then
information which is useful only to administrators of XFS
filesystems using quota and the quota commands which allow
modifications to the quota system.
Note that common to almost all of the individual commands
described below are the options for specifying which quota types
are of interest - user quota (-u), group quota (-g), and/or
project quota (-p). Also, several commands provide options to
operate on "blocks used" (-b), "inodes used" (-i), and/or
"realtime blocks used" (-r).
Many commands also have extensive online help. Use the help
command for more details on any command.
In most computing environments, disk space is not infinite. The
quota subsystem provides a mechanism to control usage of disk
space. Quotas can be set for each individual user on any/all of
the local filesystems. The quota subsystem warns users when they
exceed their allotted limit, but allows some extra space for
current work (hard limit/soft limit). In addition, XFS
filesystems with limit enforcement turned off can be used as an
effective disk usage accounting system.
Users' View of Disk Quotas
To most users, disk quotas are either of no concern or a fact of
life that cannot be avoided. There are two possible quotas that
can be imposed - a limit can be set on the amount of space a user
can occupy, and there may be a limit on the number of files
(inodes) they can own.
The quota command provides information on the quotas that have
been set by the system administrators and current usage.
There are four numbers for each limit: current usage, soft limit
(quota), hard limit, and time limit. The soft limit is the
number of 1K-blocks (or files) that the user is expected to
remain below. The hard limit cannot be exceeded. If a user's
usage reaches the hard limit, further requests for space (or
attempts to create a file) fail with the "Quota exceeded"
(EDQUOT) error.
When a user exceeds the soft limit, the timer is enabled. Any
time the quota drops below the soft limits, the timer is
disabled. If the timer pops, the particular limit that has been
exceeded is treated as if the hard limit has been reached, and no
more resources are allocated to the user. The only way to reset
this condition, short of turning off limit enforcement or
increasing the limit, is to reduce usage below quota. Only the
superuser (i.e. a sufficiently capable process) can set the time
limits and this is done on a per filesystem basis.
Surviving When the Quota Limit Is Reached
In most cases, the only way for a user to recover from over-quota
conditions is to abort whatever activity is in progress on the
filesystem that has reached its limit, remove sufficient files to
bring the limit back below quota, and retry the failed program.
However, if a user is in the editor and a write fails because of
an over quota situation, that is not a suitable course of action.
It is most likely that initially attempting to write the file has
truncated its previous contents, so if the editor is aborted
without correctly writing the file, not only are the recent
changes lost, but possibly much, or even all, of the contents
that previously existed.
There are several possible safe exits for a user caught in this
situation. They can use the editor shell escape command to
examine their file space and remove surplus files.
Alternatively, using sh(1), they can suspend the editor, remove
some files, then resume it. A third possibility is to write the
file to some other filesystem (perhaps to a file on /tmp) where
the user's quota has not been exceeded. Then after rectifying
the quota situation, the file can be moved back to the filesystem
it belongs on.
Default Quotas
The XFS quota subsystem allows a default quota to be enforced for
any user, group or project which does not have a quota limit
explicitly set. These limits are stored in and displayed as ID
0's limits, although they do not actually limit ID 0.
print Lists all paths with devices/project identifiers. The
path list can come from several places - the command line,
the mount table, and the /etc/projects file.
df See the free command.
quota [ -g | -p | -u ] [ -bir ] [ -hnNv ] [ -f file ] [ ID | name
] ...
Show individual usage and limits, for a single user name
or numeric user ID. The -h option reports in a "human-
readable" format similar to the df(1) command. The -n
option reports the numeric IDs rather than the name. The
-N option omits the header. The -v option outputs verbose
information. The -f option sends the output to file
instead of stdout.
free [ -bir ] [ -hN ] [ -f file ]
Reports filesystem usage, much like the df(1) utility. It
can show usage for blocks, inode, and/or realtime block
space, and shows used, free, and total available. If
project quota are in use (see the DIRECTORY TREE QUOTA
section below), it will also report utilisation for those
projects (directory trees). The -h option reports in a
"human-readable" format. The -N option omits the header.
The -f option outputs the report to file instead of
stdout.
help [ command ]
Online help for all commands, or one specific command.
quit Exit xfs_quota.
q See the quit command.
The XFS quota system differs to that of other filesystems in a
number of ways. Most importantly, XFS considers quota
information as filesystem metadata and uses journaling to provide
a higher level guarantee of consistency. As such, it is
administered differently, in particular:
1. The quotacheck command has no effect on XFS filesystems.
The first time quota accounting is turned on (at mount
time), XFS does an automatic quotacheck internally;
afterwards, the quota system will always be completely
consistent until quotas are manually turned off.
2. There is no need for quota file(s) in the root of the XFS
filesystem.
3. XFS distinguishes between quota accounting and limit
enforcement. Quota accounting must be turned on at the
time of mounting the XFS filesystem. However, it is
possible to turn on/off limit enforcement any time quota
accounting is turned on. The "quota" option to the mount
command turns on both (user) quota accounting and
enforcement. The "uqnoenforce" option must be used to
turn on user accounting with limit enforcement disabled.
4. Turning on quotas on the root filesystem is slightly
different from the above. For Linux XFS, the quota mount
flags must be passed in with the "rootflags=" boot
parameter.
5. It is useful to use the state to monitor the XFS quota
subsystem at various stages - it can be used to see if
quotas are turned on, and also to monitor the space
occupied by the quota system itself..
6. There is a mechanism built into xfsdump that allows quota
limit information to be backed up for later restoration,
should the need arise.
7. Quota limits cannot be set before turning on quotas on.
8. XFS filesystems keep quota accounting on the superuser
(user ID zero), and the tool will display the superuser's
usage information. However, limits are never enforced on
the superuser (nor are they enforced for group and project
ID zero).
9. XFS filesystems perform quota accounting whether the user
has quota limits or not.
10. XFS supports the notion of project quota, which can be
used to implement a form of directory tree quota (i.e. to
restrict a directory tree to only being able to use up a
component of the filesystems available space; or simply to
keep track of the amount of space used, or number of
inodes, within the tree).
path [ N ]
Lists all paths with devices/project identifiers or set
the current path to the Nth list entry (the current path
is used by many of the commands described here, it
identifies the filesystem toward which a command is
directed). The path list can come from several places -
the command line, the mount table, and the /etc/projects
file.
report [ -gpu ] [ -bir ] [ -ahntlLNU ] [ -f file ]
Report filesystem quota information. This reports all
quota usage for a filesystem, for the specified quota type
(u/g/p and/or blocks/inodes/realtime). It reports blocks
in 1KB units by default. The -h option reports in a
"human-readable" format similar to the df(1) command. The
-f option outputs the report to file instead of stdout.
The -a option reports on all filesystems. By default,
outputs the name of the user/group/project. If no name is
defined for a given ID, outputs the numeric ID instead.
The -n option outputs the numeric ID instead of the name.
The -L and -U options specify lower and/or upper ID bounds
to report on. If upper/lower bounds are specified, then
by default only the IDs will be displayed in output; with
the -l option, a lookup will be performed to translate
these IDs to names. The -N option reports information
without the header line. The -t option performs a terse
report.
state [ -gpu ] [ -av ] [ -f file ]
Report overall quota state information. This reports on
the state of quota accounting, quota enforcement, and the
number of extents being used by quota metadata within the
filesystem. The -f option outputs state information to
file instead of stdout. The -a option reports state on all
filesystems and not just the current path.
limit [ -g | -p | -u ] bsoft=N | bhard=N | isoft=N | ihard=N |
rtbsoft=N | rtbhard=N -d | id | name
Set quota block limits (bhard/bsoft), inode count limits
(ihard/isoft) and/or realtime block limits
(rtbhard/rtbsoft) to N, where N is a number representing
bytes or inodes. For block limits, a number with a
s/b/k/m/g/t/p/e multiplication suffix as described in
mkfs.xfs(8) is also accepted. For inode limits, no
suffixes are allowed. The -d option (defaults) can be
used to set the default value that will be used, otherwise
a specific user/group/project name or numeric identifier
must be specified.
timer [ -g | -p | -u ] [ -bir ] value [ -d | id | name ]
Allows the quota enforcement timeout (i.e. the amount of
time allowed to pass before the soft limits are enforced
as the hard limits) to be modified. The current timeout
setting can be displayed using the state command.
When setting the default timer via the -d option, or for
id 0, or if no argument is given after value the value
argument is a number of seconds indicating the relative
amount of time after soft limits are exceeded, before hard
limits are enforced.
When setting any other individual timer by id or name, the
value is the number of seconds from now, at which time the
hard limits will be enforced. This allows extending the
grace time of an individual user who has exceeded soft
limits.
For value, units of 'minutes', 'hours', 'days', and
'weeks' are also understood (as are their abbreviations
'm', 'h', 'd', and 'w').
warn [ -g | -p | -u ] [ -bir ] value -d | id | name
Allows the quota warnings limit (i.e. the number of times
a warning will be send to someone over quota) to be viewed
and modified. The -d option (defaults) can be used to set
the default time that will be used, otherwise a specific
user/group/project name or numeric identifier must be
specified. NOTE: this feature is not currently
implemented.
enable [ -gpu ] [ -v ]
Switches on quota enforcement for the filesystem
identified by the current path. This requires the
filesystem to have been mounted with quota enabled, and
for accounting to be currently active. The -v option
(verbose) displays the state after the operation has
completed.
disable [ -gpu ] [ -v ]
Disables quota enforcement, while leaving quota accounting
active. The -v option (verbose) displays the state after
the operation has completed.
off [ -gpu ] [ -v ]
Permanently switches quota off for the filesystem
identified by the current path. Quota can only be
switched back on subsequently by unmounting and then
mounting again.
remove [ -gpu ] [ -v ]
Remove any space allocated to quota metadata from the
filesystem identified by the current path. Quota must not
be enabled on the filesystem, else this operation will
report an error.
dump [ -g | -p | -u ] [ -L | -U ] [ -f file ]
Dump out quota limit information for backup utilities,
either to standard output (default) or to a file. The -L
and -U options specify lower and/or upper ID bounds to
dump. This is only the limits, not the usage information,
of course.
restore [ -g | -p | -u ] [ -f file ]
Restore quota limits from a backup file. The file must be
in the format produced by the dump command.
quot [ -g | -p | -u ] [ -bir ] [ -acnv ] [ -f file ]
Summarize filesystem ownership, by user, group or project.
This command uses a special XFS "bulkstat" interface to
quickly scan an entire filesystem and report usage
information. This command can be used even when
filesystem quota are not enabled, as it is a full-
filesystem scan (it may also take a long time...). The -a
option displays information on all filesystems. The -c
option displays a histogram instead of a report. The -n
option displays numeric IDs rather than names. The -v
option displays verbose information. The -f option send
the output to file instead of stdout.
project [ -cCs [ -d depth ] [ -p path ] id | name ]
The -c, -C, and -s options allow the directory tree quota
mechanism to be maintained. -d allows one to limit
recursion level when processing project directories and -p
allows one to specify project paths at command line (
instead of /etc/projects ). All options are discussed in
detail below.
The project quota mechanism in XFS can be used to implement a
form of directory tree quota, where a specified directory and all
of the files and subdirectories below it (i.e. a tree) can be
restricted to using a subset of the available space in the
filesystem.
A managed tree must be setup initially using the -s option to the
project command. The specified project name or identifier is
matched to one or more trees defined in /etc/projects, and these
trees are then recursively descended to mark the affected inodes
as being part of that tree. This process sets an inode flag and
the project identifier on every file in the affected tree. Once
this has been done, new files created in the tree will
automatically be accounted to the tree based on their project
identifier. An attempt to create a hard link to a file in the
tree will only succeed if the project identifier matches the
project identifier for the tree. The xfs_io utility can be used
to set the project ID for an arbitrary file, but this can only be
done by a privileged user.
A previously setup tree can be cleared from project quota control
through use of the project -C option, which will recursively
descend the tree, clearing the affected inodes from project quota
control.
Finally, the project -c option can be used to check whether a
tree is setup, it reports nothing if the tree is correct,
otherwise it reports the paths of inodes which do not have the
project ID of the rest of the tree, or if the inode flag is not
set.
Option -d can be used to limit recursion level (-1 is infinite, 0
is top level only, 1 is first level ... ). Option -p adds
possibility to specify project paths in command line without a
need for /etc/projects to exist. Note that if projects file
exists then it is also used.
Enabling quota enforcement on an XFS filesystem (restrict a user
to a set amount of space).
# mount -o uquota /dev/xvm/home /home
# xfs_quota -x -c 'limit bsoft=500m bhard=550m tanya' /home
# xfs_quota -x -c report /home
Enabling project quota on an XFS filesystem (restrict files in
log file directories to only using 1 gigabyte of space).
# mount -o prjquota /dev/xvm/var /var
# echo 42:/var/log >> /etc/projects
# echo logfiles:42 >> /etc/projid
# xfs_quota -x -c 'project -s logfiles' /var
# xfs_quota -x -c 'limit -p bhard=1g logfiles' /var
Same as above without a need for configuration files.
# rm -f /etc/projects /etc/projid
# mount -o prjquota /dev/xvm/var /var
# xfs_quota -x -c 'project -s -p /var/log 42' /var
# xfs_quota -x -c 'limit -p bhard=1g 42' /var
The XFS allocation mechanism will always reserve the maximum
amount of space required before proceeding with an allocation.
If insufficient space for this reservation is available, due to
the block quota limit being reached for example, this may result
in the allocation failing even though there is sufficient space.
Quota enforcement can thus sometimes happen in situations where
the user is under quota and the end result of some operation
would still have left the user under quota had the operation been
allowed to run its course. This additional overhead is typically
in the range of tens of blocks.
Both of these properties are unavoidable side effects of the way
XFS operates, so should be kept in mind when assigning block
limits.
Quota support for filesystems with realtime subvolumes is not yet
implemented, nor is the quota warning mechanism (the Linux
warnquota(8) tool can be used to provide similar functionality on
that platform).
/etc/projects
Mapping of numeric project identifiers to directories
trees.
/etc/projid
Mapping of numeric project identifiers to project names.
df(1), mount(1), sync(2), projid(5), projects(5). xfs(5).
warnquota(8),
This page is part of the xfsprogs (utilities for XFS filesystems)
project. Information about the project can be found at
⟨http://xfs.org/⟩. If you have a bug report for this manual page,
send it to [email protected]. This page was obtained
from the project's upstream Git repository
⟨https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git⟩ on
2024-06-14. (At that time, the date of the most recent commit
that was found in the repository was 2024-05-17.) If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to [email protected]
xfs_quota(8)
Pages that refer to this page: projects(5), projid(5), xfsdump(8), xfs_io(8), xfsrestore(8)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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