1 <?xml version='1.0' encoding='utf-8'?>
2 <chapter xmlns="http://docbook.org/ns/docbook"
3 xmlns:xl="http://www.w3.org/1999/xlink" version="5.0" xml:lang="en-US"
4 xml:id="configuringquotas">
5 <title xml:id="configuringquotas.title">Configuring and Managing
7 <section xml:id="quota_configuring">
10 <primary>Quotas</primary>
11 <secondary>configuring</secondary>
12 </indexterm>Working with Quotas</title>
13 <para>Quotas allow a system administrator to limit the amount of disk
14 space a user, group, or project can use. Quotas are set by root, and can
15 be specified for individual users, groups, and/or projects. Before a file
16 is written to a partition where quotas are set, the quota of the creator's
17 group is checked. If a quota exists, then the file size counts towards
18 the group's quota. If no quota exists, then the owner's user quota is
19 checked before the file is written. Similarly, inode usage for specific
20 functions can be controlled if a user over-uses the allocated space.</para>
21 <para>Lustre quota enforcement differs from standard Linux quota
22 enforcement in several ways:</para>
25 <para>Quotas are administered via the
26 <literal>lfs</literal> and
27 <literal>lctl</literal> commands (post-mount).</para>
30 <para>The quota feature in Lustre software is distributed
31 throughout the system (as the Lustre file system is a distributed file
32 system). Because of this, quota setup and behavior on Lustre is
33 somewhat different from local disk quotas in the following ways:</para>
36 <para>No single point of administration: some commands must be
37 executed on the MGS, other commands on the MDSs and OSSs, and still
38 other commands on the client.</para>
41 <para>Granularity: a local quota is typically specified for
42 kilobyte resolution, Lustre uses one megabyte as the smallest quota
46 <para>Accuracy: quota information is distributed throughout the file
47 system and can only be accurately calculated with a quiescent file
48 system in order to minimize performance overhead during normal use.
54 <para>Quotas are allocated and consumed in a quantized fashion.</para>
57 <para>Client does not set the
58 <literal>usrquota</literal> or
59 <literal>grpquota</literal> options to mount. Space accounting is
60 enabled by default and quota enforcement can be enabled/disabled on
61 a per-filesystem basis with <literal>lctl conf_param</literal>.</para>
62 <para condition="l28">It is worth noting that the
63 <literal>lfs quotaon</literal>, <literal>lfs quotaoff</literal>,
64 <literal>lfs quotacheck</literal> and <literal>quota_type</literal>
65 sub-commands are deprecated as of Lustre 2.4.0, and removed completely
66 in Lustre 2.8.0.</para>
70 <para>Although a quota feature is available in the Lustre software, root
71 quotas are NOT enforced.</para>
73 <literal>lfs setquota -u root</literal> (limits are not enforced)</para>
75 <literal>lfs quota -u root</literal> (usage includes internal Lustre data
76 that is dynamic in size and does not accurately reflect mount point
77 visible block and inode usage).</para>
80 <section xml:id="enabling_disk_quotas">
83 <primary>Quotas</primary>
84 <secondary>enabling disk</secondary>
85 </indexterm>Enabling Disk Quotas</title>
86 <para>The design of quotas on Lustre has management and enforcement
87 separated from resource usage and accounting. Lustre software is
88 responsible for management and enforcement. The back-end file
89 system is responsible for resource usage and accounting. Because of
90 this, it is necessary to begin enabling quotas by enabling quotas on the
94 <para>Quota setup is orchestrated by the MGS and <emphasis>all setup
95 commands in this section must be run directly on the MGS</emphasis>.
96 Support for project quotas specifically requires Lustre Release 2.10 or
97 later. A <emphasis>patched server</emphasis> may be required, depending
98 on the kernel version and backend filesystem type:</para>
99 <informaltable frame="all">
101 <colspec colname="c1" colwidth="50*" />
102 <colspec colname="c2" colwidth="50*" align="center" />
107 <emphasis role="bold">Configuration</emphasis>
112 <emphasis role="bold">Patched Server Required?</emphasis>
120 <emphasis>ldiskfs with kernel version < 4.5</emphasis>
122 <entry><para>Yes</para></entry>
126 <emphasis>ldiskfs with kernel version >= 4.5</emphasis>
128 <entry><para>No</para></entry>
132 <emphasis>zfs version >=0.8 with kernel
133 version < 4.5</emphasis>
135 <entry><para>Yes</para></entry>
139 <emphasis>zfs version >=0.8 with kernel
140 version > 4.5</emphasis>
142 <entry><para>No</para></entry>
147 <para>*Note: Project quotas are not supported on zfs versions earlier
150 <para>Once setup, verification of the quota state must be performed on the
151 MDT. Although quota enforcement is managed by the Lustre software, each
152 OSD implementation relies on the back-end file system to maintain
153 per-user/group/project block and inode usage. Hence, differences exist
154 when setting up quotas with ldiskfs or ZFS back-ends:</para>
157 <para>For ldiskfs backends,
158 <literal>mkfs.lustre</literal> now creates empty quota files and
159 enables the QUOTA feature flag in the superblock which turns quota
160 accounting on at mount time automatically. e2fsck was also modified
161 to fix the quota files when the QUOTA feature flag is present. The
162 project quota feature is disabled by default, and
163 <literal>tune2fs</literal> needs to be run to enable every target
164 manually. If user, group, and project quota usage is inconsistent,
165 run <literal>e2fsck -f</literal> on all unmounted MDTs and OSTs.
169 <para>For ZFS backend, <emphasis>the project quota feature is not
170 supported on zfs versions less than 0.8.0.</emphasis> Accounting ZAPs
171 are created and maintained by the ZFS file system itself. While ZFS
172 tracks per-user and group block usage, it does not handle inode
173 accounting for ZFS versions prior to zfs-0.7.0. The ZFS OSD previously
174 implemented its own support for inode tracking. Two options are
178 <para>The ZFS OSD can estimate the number of inodes in-use based
179 on the number of blocks used by a given user or group. This mode
180 can be enabled by running the following command on the server
182 <literal>lctl set_param
183 osd-zfs.${FSNAME}-${TARGETNAME}.quota_iused_estimate=1</literal>.
187 <para>Similarly to block accounting, dedicated ZAPs are also
188 created the ZFS OSD to maintain per-user and group inode usage.
189 This is the default mode which corresponds to
190 <literal>quota_iused_estimate</literal> set to 0.</para>
196 <para>To (re-)enable space usage quota on ldiskfs filesystems, run
197 <literal>tune2fs -O quota</literal> against all targets. This command
198 sets the QUOTA feature flag in the superblock and runs e2fsck internally.
199 As a result, the target must be offline to build the per-UID/GID disk
200 usage database.</para>
201 <para condition="l2A">Lustre filesystems formatted with a Lustre release
202 prior to 2.10 can be still safely upgraded to release 2.10, but will not
203 have project quota usage reporting functional until 2.15.0 or
204 <literal>tune2fs -O project</literal> is run against all ldiskfs backend
205 targets. This command sets the PROJECT feature flag in the superblock and
206 runs e2fsck (as a result, the target must be offline). See
207 <xref linkend="quota_interoperability"/> for further important
208 considerations.</para>
211 <para>Lustre requires a version of e2fsprogs that supports quota
212 to be installed on the server nodes when using the ldiskfs backend
213 (e2fsprogs is not needed with ZFS backend). In general, we recommend
214 to use the latest e2fsprogs version available on
215 <link xl:href="https://downloads.whamcloud.com/public/e2fsprogs/">
216 https://downloads.whamcloud.com/public/e2fsprogs/</link>.</para>
217 <para>The ldiskfs OSD relies on the standard Linux quota to maintain
218 accounting information on disk. As a consequence, the Linux kernel
219 running on the Lustre servers using ldiskfs backend must have
220 <literal>CONFIG_QUOTA</literal>,
221 <literal>CONFIG_QUOTACTL</literal> and
222 <literal>CONFIG_QFMT_V2</literal> enabled.</para>
224 <para>Quota enforcement is turned on/off independently of space
225 accounting which is always enabled. There is a single per-file
226 system quota parameter controlling inode/block quota enforcement.
227 Like all permanent parameters, this quota parameter can be set via
228 <literal>lctl conf_param</literal> on the MGS via the command:</para>
230 lctl conf_param <replaceable>fsname</replaceable>.quota.<replaceable>ost|mdt</replaceable>=<replaceable>u|g|p|ugp|none</replaceable>
235 <literal>ost</literal> -- to configure block quota managed by
240 <literal>mdt</literal> -- to configure inode quota managed by
245 <literal>u</literal> -- to enable quota enforcement for users
250 <literal>g</literal> -- to enable quota enforcement for groups
255 <literal>p</literal> -- to enable quota enforcement for projects
260 <literal>ugp</literal> -- to enable quota enforcement for all users,
261 groups and projects</para>
265 <literal>none</literal> -- to disable quota enforcement for all users,
266 groups and projects</para>
269 <para>Examples:</para>
270 <para>To turn on user, group, and project quotas for block only on
272 <literal>testfs1</literal>, <emphasis>on the MGS</emphasis> run:</para>
273 <screen>mgs# lctl conf_param testfs1.quota.ost=ugp </screen>
274 <para>To turn on group quotas for inodes on file system
275 <literal>testfs2</literal>, on the MGS run:</para>
276 <screen>mgs# lctl conf_param testfs2.quota.mdt=g </screen>
277 <para>To turn off user, group, and project quotas for both inode and block
279 <literal>testfs3</literal>, on the MGS run:</para>
280 <screen>mgs# lctl conf_param testfs3.quota.ost=none</screen>
281 <screen>mgs# lctl conf_param testfs3.quota.mdt=none</screen>
282 <section xml:id="quota_verification">
285 <primary>Quotas</primary>
286 <secondary>verifying</secondary>
287 </indexterm>Quota Verification</title>
288 <para>Once the quota parameters have been configured, all targets
289 which are part of the file system will be automatically notified of the
290 new quota settings and enable/disable quota enforcement as needed. The
291 per-target enforcement status can still be verified by running the
292 following <emphasis>command on the MDS(s)</emphasis>:</para>
294 $ lctl get_param osd-*.*.quota_slave.info
295 osd-zfs.testfs-MDT0000.quota_slave.info=
296 target name: testfs-MDT0000
300 conn to master: setup
301 user uptodate: glb[1],slv[1],reint[0]
302 group uptodate: glb[1],slv[1],reint[0]
306 <section xml:id="quota_administration">
309 <primary>Quotas</primary>
310 <secondary>creating</secondary>
311 </indexterm>Quota Administration</title>
312 <para>Once the file system is up and running, quota limits on blocks
313 and inodes can be set for user, group, and project. This is <emphasis>
314 controlled entirely from a client</emphasis> via three quota
317 <emphasis role="bold">Grace period</emphasis>-- The period of time (in
318 seconds) within which users are allowed to exceed their soft limit. There
319 are six types of grace periods:</para>
322 <para>user block soft limit</para>
325 <para>user inode soft limit</para>
328 <para>group block soft limit</para>
331 <para>group inode soft limit</para>
334 <para>project block soft limit</para>
337 <para>project inode soft limit</para>
340 <para>The grace period applies to all users. The user block soft limit is
341 for all users who are using a blocks quota.</para>
343 <emphasis role="bold">Soft limit</emphasis> -- The grace timer is started
344 once the soft limit is exceeded. At this point, the user/group/project
345 can still allocate block/inode. When the grace time expires and if the
346 user is still above the soft limit, the soft limit becomes a hard limit
347 and the user/group/project can't allocate any new block/inode any more.
348 The user/group/project should then delete files to be under the soft limit.
349 The soft limit MUST be smaller than the hard limit. If the soft limit is
350 not needed, it should be set to zero (0).</para>
352 <emphasis role="bold">Hard limit</emphasis> -- Block or inode allocation
354 <literal>EDQUOT</literal>(i.e. quota exceeded) when the hard limit is
355 reached. The hard limit is the absolute limit. When a grace period is set,
356 one can exceed the soft limit within the grace period if under the hard
358 <para>Due to the distributed nature of a Lustre file system and the need to
359 maintain performance under load, those quota parameters may not be 100%
360 accurate. The quota settings can be manipulated via the
361 <literal>lfs</literal> command, executed on a client, and includes several
362 options to work with quotas:</para>
366 <varname>quota</varname> -- displays general quota information (disk
367 usage and limits)</para>
371 <varname>setquota</varname> -- specifies quota limits and tunes the
372 grace period. By default, the grace period is one week.</para>
377 lfs quota [-q] [-v] [-h] [-o obd_uuid] [-u|-g|-p <replaceable>uname|uid|gname|gid|projid</replaceable>] <replaceable>/mount_point</replaceable>
378 lfs quota -t {-u|-g|-p} <replaceable>/mount_point</replaceable>
379 lfs setquota {-u|--user|-g|--group|-p|--project} <replaceable>username|groupname</replaceable> [-b <replaceable>block-softlimit</replaceable>] \
380 [-B <replaceable>block_hardlimit</replaceable>] [-i <replaceable>inode_softlimit</replaceable>] \
381 [-I <replaceable>inode_hardlimit</replaceable>] <replaceable>/mount_point</replaceable>
383 <para>To display general quota information (disk usage and limits) for the
384 user running the command and his primary group, run:</para>
386 $ lfs quota /mnt/testfs
388 <para>To display general quota information for a specific user ("
389 <literal>bob</literal>" in this example), run:</para>
391 $ lfs quota -u bob /mnt/testfs
393 <para>To display general quota information for a specific user ("
394 <literal>bob</literal>" in this example) and detailed quota statistics for
395 each MDT and OST, run:</para>
397 $ lfs quota -u bob -v /mnt/testfs
399 <para>To display general quota information for a specific project ("
400 <literal>1</literal>" in this example), run:</para>
402 $ lfs quota -p 1 /mnt/testfs
404 <para>To display general quota information for a specific group ("
405 <literal>eng</literal>" in this example), run:</para>
407 $ lfs quota -g eng /mnt/testfs
409 <para>To limit quota usage for a specific project ID on a specific
410 directory ("<literal>/mnt/testfs/dir</literal>" in this example), run:</para>
412 $ lfs project -s -p 1 -r /mnt/testfs/dir
413 $ lfs setquota -p 1 -b 307200 -B 309200 -i 10000 -I 11000 /mnt/testfs
415 <para> Recursively list all descendants'(of the directory) project attribute on
416 directory ("<literal>/mnt/testfs/dir</literal>" in this example), run:</para>
418 $ lfs project -r /mnt/testfs/dir
420 <para>Please note that if it is desired to have
421 <literal>lfs quota -p</literal> show the space/inode usage under the
422 directory properly (much faster than <literal>du</literal>), then the
423 user/admin needs to use different project IDs for different directories.
425 <para>To display block and inode grace times for user quotas, run:</para>
427 $ lfs quota -t -u /mnt/testfs
429 <para>To set user or group quotas for a specific ID ("bob" in this
430 example), run:</para>
432 $ lfs setquota -u bob -b 307200 -B 309200 -i 10000 -I 11000 /mnt/testfs
434 <para>In this example, the quota for user "bob" is set to 300 MB
435 (309200*1024) and the hard limit is 11,000 files. Therefore, the inode hard
436 limit should be 11000.</para>
437 <para>The quota command displays the quota allocated and consumed by each
438 Lustre target. Using the previous
439 <literal>setquota</literal> example, running this
440 <literal>lfs</literal> quota command:</para>
442 $ lfs quota -u bob -v /mnt/testfs
444 <para>displays this command output:</para>
446 Disk quotas for user bob (uid 6000):
447 Filesystem kbytes quota limit grace files quota limit grace
448 /mnt/testfs 0 30720 30920 - 0 10000 11000 -
449 testfs-MDT0000_UUID 0 - 8192 - 0 - 2560 -
450 testfs-OST0000_UUID 0 - 8192 - 0 - 0 -
451 testfs-OST0001_UUID 0 - 8192 - 0 - 0 -
452 Total allocated inode limit: 2560, total allocated block limit: 24576
454 <para>Global quota limits are stored in dedicated index files (there is one
455 such index per quota type) on the quota master target (aka QMT). The QMT
456 runs on MDT0000 and exports the global indices via <replaceable>lctl
457 get_param</replaceable>. The global indices can thus be dumped via the
460 # lctl get_param qmt.testfs-QMT0000.*.glb-*
461 </screen>The format of global indexes depends on the OSD type. The ldiskfs OSD
462 uses an IAM files while the ZFS OSD creates dedicated ZAPs.</para>
463 <para>Each slave also stores a copy of this global index locally. When the
464 global index is modified on the master, a glimpse callback is issued on the
465 global quota lock to notify all slaves that the global index has been
466 modified. This glimpse callback includes information about the identifier
467 subject to the change. If the global index on the QMT is modified while a
468 slave is disconnected, the index version is used to determine whether the
469 slave copy of the global index isn't up to date any more. If so, the slave
470 fetches the whole index again and updates the local copy. The slave copy of
471 the global index can also be accessed via the following command:
473 lctl get_param osd-*.*.quota_slave.limit*
476 <section condition='l2C' xml:id="default_quota">
479 <primary>Quotas</primary>
480 <secondary>default</secondary>
481 </indexterm>Default Quota</title>
482 <para>The default quota is used to enforce the quota limits for any user,
483 group, or project that do not have quotas set by administrator.</para>
484 <para>The default quota can be disabled by setting limits to
485 <literal>0</literal>.</para>
486 <section xml:id="defalut_quota_usage">
489 <primary>Quotas</primary>
490 <secondary>usage</secondary>
491 </indexterm>Usage</title>
493 lfs quota [-U|--default-usr|-G|--default-grp|-P|--default-prj] <replaceable>/mount_point</replaceable>
494 lfs setquota {-U|--default-usr|-G|--default-grp|-P|--default-prj} [-b <replaceable>block-softlimit</replaceable>] \
495 [-B <replaceable>block_hardlimit</replaceable>] [-i <replaceable>inode_softlimit</replaceable>] [-I <replaceable>inode_hardlimit</replaceable>] <replaceable>/mount_point</replaceable>
496 lfs setquota {-u|-g|-p} <replaceable>username|groupname</replaceable> -d <replaceable>/mount_point</replaceable>
498 <para>To set the default user quota:</para>
500 # lfs setquota -U -b 10G -B 11G -i 100K -I 105K /mnt/testfs
502 <para>To set the default group quota:</para>
504 # lfs setquota -G -b 10G -B 11G -i 100K -I 105K /mnt/testfs
506 <para>To set the default project quota:</para>
508 # lfs setquota -P -b 10G -B 11G -i 100K -I 105K /mnt/testfs
510 <para>To disable the default user quota:</para>
512 # lfs setquota -U -b 0 -B 0 -i 0 -I 0 /mnt/testfs
514 <para>To disable the default group quota:</para>
516 # lfs setquota -G -b 0 -B 0 -i 0 -I 0 /mnt/testfs
518 <para>To disable the default project quota:</para>
520 # lfs setquota -P -b 0 -B 0 -i 0 -I 0 /mnt/testfs
524 If quota limits are set for some user, group or project, it will use
525 those specific quota limits instead of the default quota. Quota limits for
526 any user, group or project will use the default quota by setting its quota
527 limits to <literal>0</literal>.
532 <section xml:id="quota_allocation">
535 <primary>Quotas</primary>
536 <secondary>allocating</secondary>
537 </indexterm>Quota Allocation</title>
538 <para>In a Lustre file system, quota must be properly allocated or users
539 may experience unnecessary failures. The file system block quota is divided
540 up among the OSTs within the file system. Each OST requests an allocation
541 which is increased up to the quota limit. The quota allocation is then
542 <emphasis role="italic">quantized</emphasis> to reduce the number of
543 quota-related request traffic.</para>
544 <para>The Lustre quota system distributes quotas from the Quota Master
545 Target (aka QMT). Only one QMT instance is supported for now and only runs
546 on the same node as MDT0000. All OSTs and MDTs set up a Quota Slave Device
547 (aka QSD) which connects to the QMT to allocate/release quota space. The
548 QSD is setup directly from the OSD layer.</para>
549 <para>To reduce quota requests, quota space is initially allocated to QSDs
550 in very large chunks. How much unused quota space can be held by a target
551 is controlled by the qunit size. When quota space for a given ID is close
552 to exhaustion on the QMT, the qunit size is reduced and QSDs are notified
553 of the new qunit size value via a glimpse callback. Slaves are then
554 responsible for releasing quota space above the new qunit value. The qunit
555 size isn't shrunk indefinitely and there is a minimal value of 1MB for
556 blocks and 1,024 for inodes. This means that the quota space rebalancing
557 process will stop when this minimum value is reached. As a result, quota
558 exceeded can be returned while many slaves still have 1MB or 1,024 inodes
559 of spare quota space.</para>
560 <para>If we look at the
561 <literal>setquota</literal> example again, running this
562 <literal>lfs quota</literal> command:</para>
564 # lfs quota -u bob -v /mnt/testfs
566 <para>displays this command output:</para>
568 Disk quotas for user bob (uid 500):
569 Filesystem kbytes quota limit grace files quota limit grace
570 /mnt/testfs 30720* 30720 30920 6d23h56m44s 10101* 10000 11000
572 testfs-MDT0000_UUID 0 - 0 - 10101 - 10240
573 testfs-OST0000_UUID 0 - 1024 - - - -
574 testfs-OST0001_UUID 30720* - 29896 - - - -
575 Total allocated inode limit: 10240, total allocated block limit: 30920
577 <para>The total quota limit of 30,920 is allocated to user bob, which is
578 further distributed to two OSTs.</para>
579 <para>Values appended with '
580 <literal>*</literal>' show that the quota limit has been exceeded, causing
581 the following error when trying to write or create a file:</para>
584 $ cp: writing `/mnt/testfs/foo`: Disk quota exceeded.
588 <para>It is very important to note that the block quota is consumed per
589 OST and the inode quota per MDS. Therefore, when the quota is consumed on
590 one OST (resp. MDT), the client may not be able to create files
591 regardless of the quota available on other OSTs (resp. MDTs).</para>
592 <para>Setting the quota limit below the minimal qunit size may prevent
593 the user/group from all file creation. It is thus recommended to use
594 soft/hard limits which are a multiple of the number of OSTs * the minimal
597 <para>To determine the total number of inodes, use
598 <literal>lfs df -i</literal>(and also
599 <literal>lctl get_param *.*.filestotal</literal>). For more information on
601 <literal>lfs df -i</literal> command and the command output, see
602 <xref linkend="file_striping.checking_free_space" />.</para>
603 <para>Unfortunately, the
604 <literal>statfs</literal> interface does not report the free inode count
605 directly, but instead reports the total inode and used inode counts. The
606 free inode count is calculated for
607 <literal>df</literal> from (total inodes - used inodes). It is not critical
608 to know the total inode count for a file system. Instead, you should know
609 (accurately), the free inode count and the used inode count for a file
610 system. The Lustre software manipulates the total inode count in order to
611 accurately report the other two values.</para>
613 <section xml:id="quota_interoperability">
616 <primary>Quotas</primary>
617 <secondary>Interoperability</secondary>
618 </indexterm>Quotas and Version Interoperability</title>
619 <para condition="l2A">To use the project quota functionality introduced in
620 Lustre 2.10, <emphasis role="bold">all Lustre servers and clients must be
621 upgraded to Lustre release 2.10 or later for project quota to work
622 correctly</emphasis>. Otherwise, project quota will be inaccessible on
623 clients and not be accounted for on OSTs. Furthermore, the
624 <emphasis role="bold">servers may be required to use a patched kernel,
625 </emphasis> for more information see
626 <xref linkend="enabling_disk_quotas"/>.</para>
627 <para condition="l2E"><literal>df</literal> and <literal>lfs df</literal>
628 will return the amount of space available to that project rather than the
629 total filesystem space, if the project quota limit is smaller.
630 <emphasis role="bold"> Only client need be upgraded to Lustre
631 release 2.14 or later to apply this new behavior</emphasis>.</para>
633 <section xml:id="granted_cache_and_quota_limits">
636 <primary>Quotas</primary>
637 <secondary>known issues</secondary>
638 </indexterm>Granted Cache and Quota Limits</title>
639 <para>In a Lustre file system, granted cache does not respect quota limits.
640 In this situation, OSTs grant cache to a Lustre client to accelerate I/O.
641 Granting cache causes writes to be successful in OSTs, even if they exceed
642 the quota limits, and will overwrite them.</para>
643 <para>The sequence is:</para>
646 <para>A user writes files to the Lustre file system.</para>
649 <para>If the Lustre client has enough granted cache, then it returns
650 'success' to users and arranges the writes to the OSTs.</para>
653 <para>Because Lustre clients have delivered success to users, the OSTs
654 cannot fail these writes.</para>
657 <para>Because of granted cache, writes always overwrite quota limitations.
658 For example, if you set a 400 GB quota on user A and use IOR to write for
659 user A from a bundle of clients, you will write much more data than 400 GB,
660 and cause an out-of-quota error (
661 <literal>EDQUOT</literal>).</para>
663 <para>The effect of granted cache on quota limits can be mitigated, but
664 not eradicated. Reduce the maximum amount of dirty data on the clients
665 (minimal value is 1MB):</para>
669 <literal>lctl set_param osc.*.max_dirty_mb=8</literal>
675 <section xml:id="lustre_quota_statistics">
678 <primary>Quotas</primary>
679 <secondary>statistics</secondary>
680 </indexterm>Lustre Quota Statistics</title>
681 <para>The Lustre software includes statistics that monitor quota activity,
682 such as the kinds of quota RPCs sent during a specific period, the average
683 time to complete the RPCs, etc. These statistics are useful to measure
684 performance of a Lustre file system.</para>
685 <para>Each quota statistic consists of a quota event and
686 <literal>min_time</literal>,
687 <literal>max_time</literal> and
688 <literal>sum_time</literal> values for the event.</para>
689 <informaltable frame="all">
691 <colspec colname="c1" colwidth="50*" />
692 <colspec colname="c2" colwidth="50*" />
697 <emphasis role="bold">Quota Event</emphasis>
702 <emphasis role="bold">Description</emphasis>
711 <emphasis role="bold">sync_acq_req</emphasis>
715 <para>Quota slaves send a acquiring_quota request and wait for
722 <emphasis role="bold">sync_rel_req</emphasis>
726 <para>Quota slaves send a releasing_quota request and wait for
733 <emphasis role="bold">async_acq_req</emphasis>
737 <para>Quota slaves send an acquiring_quota request and do not
738 wait for its return.</para>
744 <emphasis role="bold">async_rel_req</emphasis>
748 <para>Quota slaves send a releasing_quota request and do not wait
749 for its return.</para>
755 <emphasis role="bold">wait_for_blk_quota
756 (lquota_chkquota)</emphasis>
760 <para>Before data is written to OSTs, the OSTs check if the
761 remaining block quota is sufficient. This is done in the
762 lquota_chkquota function.</para>
768 <emphasis role="bold">wait_for_ino_quota
769 (lquota_chkquota)</emphasis>
773 <para>Before files are created on the MDS, the MDS checks if the
774 remaining inode quota is sufficient. This is done in the
775 lquota_chkquota function.</para>
781 <emphasis role="bold">wait_for_blk_quota
782 (lquota_pending_commit)</emphasis>
786 <para>After blocks are written to OSTs, relative quota
787 information is updated. This is done in the lquota_pending_commit
794 <emphasis role="bold">wait_for_ino_quota
795 (lquota_pending_commit)</emphasis>
799 <para>After files are created, relative quota information is
800 updated. This is done in the lquota_pending_commit
807 <emphasis role="bold">wait_for_pending_blk_quota_req
808 (qctxt_wait_pending_dqacq)</emphasis>
812 <para>On the MDS or OSTs, there is one thread sending a quota
813 request for a specific UID/GID for block quota at any time. At
814 that time, if other threads need to do this too, they should
815 wait. This is done in the qctxt_wait_pending_dqacq
822 <emphasis role="bold">wait_for_pending_ino_quota_req
823 (qctxt_wait_pending_dqacq)</emphasis>
827 <para>On the MDS, there is one thread sending a quota request for
828 a specific UID/GID for inode quota at any time. If other threads
829 need to do this too, they should wait. This is done in the
830 qctxt_wait_pending_dqacq function.</para>
836 <emphasis role="bold">nowait_for_pending_blk_quota_req
837 (qctxt_wait_pending_dqacq)</emphasis>
841 <para>On the MDS or OSTs, there is one thread sending a quota
842 request for a specific UID/GID for block quota at any time. When
843 threads enter qctxt_wait_pending_dqacq, they do not need to wait.
844 This is done in the qctxt_wait_pending_dqacq function.</para>
850 <emphasis role="bold">nowait_for_pending_ino_quota_req
851 (qctxt_wait_pending_dqacq)</emphasis>
855 <para>On the MDS, there is one thread sending a quota request for
856 a specific UID/GID for inode quota at any time. When threads
857 enter qctxt_wait_pending_dqacq, they do not need to wait. This is
858 done in the qctxt_wait_pending_dqacq function.</para>
864 <emphasis role="bold">quota_ctl</emphasis>
868 <para>The quota_ctl statistic is generated when lfs
869 <literal>setquota</literal>,
870 <literal>lfs quota</literal> and so on, are issued.</para>
876 <emphasis role="bold">adjust_qunit</emphasis>
880 <para>Each time qunit is adjusted, it is counted.</para>
887 <title>Interpreting Quota Statistics</title>
888 <para>Quota statistics are an important measure of the performance of a
889 Lustre file system. Interpreting these statistics correctly can help you
890 diagnose problems with quotas, and may indicate adjustments to improve
891 system performance.</para>
892 <para>For example, if you run this command on the OSTs:</para>
894 lctl get_param lquota.testfs-OST0000.stats
896 <para>You will get a result similar to this:</para>
898 snapshot_time 1219908615.506895 secs.usecs
899 async_acq_req 1 samples [us] 32 32 32
900 async_rel_req 1 samples [us] 5 5 5
901 nowait_for_pending_blk_quota_req(qctxt_wait_pending_dqacq) 1 samples [us] 2\
903 quota_ctl 4 samples [us] 80 3470 4293
904 adjust_qunit 1 samples [us] 70 70 70
907 <para>In the first line,
908 <literal>snapshot_time</literal> indicates when the statistics were taken.
909 The remaining lines list the quota events and their associated
911 <para>In the second line, the
912 <literal>async_acq_req</literal> event occurs one time. The
913 <literal>min_time</literal>,
914 <literal>max_time</literal> and
915 <literal>sum_time</literal> statistics for this event are 32, 32 and 32,
916 respectively. The unit is microseconds (μs).</para>
917 <para>In the fifth line, the quota_ctl event occurs four times. The
918 <literal>min_time</literal>,
919 <literal>max_time</literal> and
920 <literal>sum_time</literal> statistics for this event are 80, 3470 and
921 4293, respectively. The unit is microseconds (μs).</para>
924 <section xml:id="quota_pools" condition='l2E'>
927 <primary>Quotas</primary>
928 <secondary>pools</secondary>
929 </indexterm>Pool Quotas</title>
931 OST Pool Quotas feature gives an ability to limit user's (group's/project's)
932 disk usage at OST pool level. Each OST Pool Quota (PQ) maps directly to the
933 OST pool of the same name. Thus PQ could be tuned with standard <literal>
934 lctl pool_new/add/remove/erase</literal> commands. All PQ are subset of a
935 global pool that includes all OSTs and MDTs (DOM case).
936 It may be initially confusing to be prevented from using "all of" one quota
937 due to a different quota setting. In Lustre, a quota is a limit, not a right
938 to use an amount. You don't always get to use your quota - an OST may be out
939 of space, or some other quota is limiting. For example, if there is an inode
940 quota and a space quota, and you hit your inode limit while you still have
941 plenty of space, you can't use the space. For another example, quotas may
942 easily be over-allocated: everyone gets 10PB of quota, in a 15PB system.
943 That does not give them the right to use 10PB, it means they cannot use more
944 than 10PB. They may very well get ENOSPC long before that - but they will not
945 get EDQUOT. This behavior already exists in Lustre today, but pool quotas
946 increase the number of limits in play: user, group or project global space quota
947 and now all of those limits can also be defined for each pool. In all cases,
948 the net effect is that the actual amount of space you can use is limited to the
949 smallest (min) quota out of everything that is applicable.
951 <link xl:href="http://wiki.lustre.org/OST_Pool_Quotas_HLD">
952 OST Pool Quotas HLD</link>
955 <title>DOM and MDT pools</title>
957 From Quota Master point of view, "data" MDTs are regular members together
958 with OSTs. However Pool Quotas support only OSTs as there is currently
959 no mechanism to group MDTs in pools.
963 <title>Lfs quota/setquota options to setup quota pools</title>
965 The same long option <literal>--pool</literal> is used to setup and report
966 Pool Quotas with <literal>lfs setquota</literal> and <literal>lfs setquota</literal>.
969 <literal>lfs setquota --pool <replaceable>pool_name</replaceable></literal>
970 is used to set the block and soft usage limit for the user, group, or
971 project for the specified pool name.
974 <literal>lfs quota --pool <replaceable>pool_name</replaceable></literal>
975 shows the user, group, or project usage for the specified pool name.
979 <title>Quota pools interoperability</title>
981 Both client and server should have at least Lustre 2.14 to support Pool Quotas.
984 <para>Pool Quotas may be able to work with older clients if server
985 supports Pool Quotas. Pool quotas cannot be viewed or modified by
986 older clients. Since the quota enforcement is done on the servers, only
987 a single client is needed to configure the quotas. This could be done by
988 mounting a client directly on the MDS if needed.
993 <title>Pool Quotas Hard Limit setup example</title>
995 Let's imagine you need to setup quota usage for already existed OST pool
996 <literal>flash_pool</literal>:
999 # it is a limit for global pool. PQ don't work properly without that
1000 lfs setquota -u <replaceable>ivan</replaceable> -B<replaceable>100T /mnt/testfs</replaceable>
1001 # set 1TiB block hard limit for ivan in a flash_pool
1002 lfs setquota -u <replaceable>ivan</replaceable> --pool <replaceable>flash_pool</replaceable> -B<replaceable>1T /mnt/testfs</replaceable>
1006 <para>System-side hard limit is required before setting Quota Pool limit.
1007 If you do not need to limit user at all OSTs and MDTs at system,
1008 only per pool, it is recommended to set some unrealistic big hard limit.
1009 Without a global limit in place the Quota Pool limit will not be enforced.
1010 No matter hard or soft global limit - at least one of them should be set.
1015 <section remap="h3">
1016 <title>Pool Quotas Soft Limit setup example</title>
1018 # notify OSTs to enforce quota for ivan
1019 lfs setquota -u <replaceable>ivan</replaceable> -B<replaceable>10T /mnt/testfs</replaceable>
1020 # soft limit 10MiB for ivan in a pool flash_pool
1021 lfs setquota -u <replaceable>ivan</replaceable> --pool <replaceable>flash_pool</replaceable> -b<replaceable>1T /mnt/testfs</replaceable>
1022 # set block grace 600 s for all users at flash_pool
1023 lfs setquota -t -u --block-grace <replaceable>600</replaceable> --pool <replaceable>flash_pool /mnt/testfs</replaceable>
1029 vim:expandtab:shiftwidth=2:tabstop=8: