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    Command:

    xfs_quota

    
    
    

    SYNOPSIS

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

    DESCRIPTION

           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 modifi-
                     cations  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 individ-
           ual  xfs_quota  commands will then be restricted to the set of filesys-
           tems 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.
    
    
    

    QUOTA OVERVIEW

           In  most computing environments, disk space is not infinite.  The quota
           subsystem provides a mechanism to control usage of disk space.   Quotas
    
           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 con-
           ditions 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 situa-
           tion.  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  possi-
           bility 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 rec-
           tifying the quota situation, the file can be moved back to the filesys-
           tem it belongs on.
    
    
    

    USER COMMANDS

           print  Lists all paths with devices/project identifiers.  The path list
                  can  come  from several places - the command line, the mount ta-
                  ble, 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.
    
    
           q      See the quit command.
    
    
    

    QUOTA ADMINISTRATION

           The XFS quota system differs to that of other filesystems in  a  number
           of ways.  Most importantly, XFS considers quota information as filesys-
           tem 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  enforce-
                  ment.   Quota accounting must be turned on at the time of mount-
                  ing 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 IRIX XFS, refer to quotaon(1M).  For  Linux
                  XFS,  the  quota  mount  flags must be passed in with the "root-
                  flags=" 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  informa-
                  tion.   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
                  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 filesys-
                  tems. 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 | rtb-
                  hard=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 dis-
                  played 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 ]
           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 lim-
                  its, 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
                  stdout.
    
           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/pro-
                  jid 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 spec-
                  ify  project paths at command line ( instead of /etc/projects ).
                  All options are discussed in detail below.
    
    
    

    DIRECTORY TREE QUOTA

           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.
           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
    
    
    

    CAVEATS

           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 maxi-
           mum  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 alloca-
           tion 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.
    
    
    

    BUGS

           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).
    
    
    

    FILES

           /etc/projects       Mapping  of numeric project identifiers to directo-
                               ries trees.
    
                                                                      xfs_quota(8)
    
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