Man Linux: Main Page and Category List


       xfs_quota - manage use of quota on XFS filesystems


       xfs_quota  [  -x ] [ -p prog ] [ -c cmd ] ... [ -d project ] ... [ path
       ... ]


       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.

       -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.

       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.

   UsersView 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) he 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.  He can use the editor shell escape command to  examine  his
       file  space  and  remove surplus files.  Alternatively, using sh(1), he
       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.


       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 [ -gpu ] [ -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

       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

       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

       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

       4.     Turning on quotas on the root filesystem is  slightly  different
              from  the above.  For IRIX XFS, refer to quotaon(1M).  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

       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 patch  list
              can  come  from  several  places  -  the command line, the mount
              table, and the /etc/projects file.

       report [ -gpu ] [ -bir ] [ -ahntLNU ] [ -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. The -n option outputs the numeric ID instead of the
              name. The -L and -U options specify lower and upper ID bounds to
              report on. 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 [ -gpu ] 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).
              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 [ -gpu ] [ -bir ] value
              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.  The  value  argument  is  a
              number  of seconds, but units of ’minutes’, ’hours’, ’days’, and
              ’weeks’ are also understood (as  are  their  abbreviations  ’m’,
              ’h’, ’d’, and ’w’).

       warn [ -gpu ] [ -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 [ -gpu ] [ -f file ]
              Dump out quota limit information for backup utilities, either to
              standard  output  (default)  or  to  a  file.   This is only the
              limits, not the usage information, of course.

       restore [ -gpu ] [ -f file ]
              Restore quota limits from a backup file.  The file  must  be  in
              the format produced by the dump command.

       quot [ -gpu ] [ -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

       project [ -cCs [ -d depth ] [ -p path ] id | name ]
              Without arguments, this command lists known  project  names  and
              identifiers   (based   on   entries  in  the  /etc/projects  and
              /etc/projid files).  The  -c,  -C,  and  -s  options  allow  the
              directory  tree  quota mechanism to be maintained.  -d allows to
              limit recursion level when processing project directories and -p
              allows  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  posibility  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


       XFS implements delayed allocation (aka. allocate-on-flush) and this has
       implications  for the quota subsystem.  Since quota accounting can only
       be done when blocks are actually allocated, it  is  possible  to  issue
       (buffered)  writes  into  a  file  and  not  see  the usage immediately
       updated.  Only when the data is actually written out, either via one of
       the  kernels  flushing  mechanisms,  or  via a manual sync(2), will the
       usage reported reflect what has actually been written.

       In addition, 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


       quotaon(1M), xfs(4).


       warnquota(8), xfs(5).


       df(1), mount(1), sync(2), projid(5), projects(5).