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="lustreoperations">
5 <title xml:id="lustreoperations.title">Lustre Operations</title>
6 <para>Once you have the Lustre file system up and running, you can use the
7 procedures in this section to perform these basic Lustre administration
9 <section xml:id="dbdoclet.50438194_42877">
12 <primary>operations</primary>
15 <primary>operations</primary>
16 <secondary>mounting by label</secondary>
17 </indexterm>Mounting by Label</title>
18 <para>The file system name is limited to 8 characters. We have encoded the
19 file system and target information in the disk label, so you can mount by
20 label. This allows system administrators to move disks around without
21 worrying about issues such as SCSI disk reordering or getting the
22 <literal>/dev/device</literal> wrong for a shared target. Soon, file system
23 naming will be made as fail-safe as possible. Currently, Linux disk labels
24 are limited to 16 characters. To identify the target within the file
25 system, 8 characters are reserved, leaving 8 characters for the file system
28 <replaceable>fsname</replaceable>-MDT0000 or
29 <replaceable>fsname</replaceable>-OST0a19
31 <para>To mount by label, use this command:</para>
34 <replaceable>file_system_label</replaceable>
35 <replaceable>/mount_point</replaceable>
37 <para>This is an example of mount-by-label:</para>
39 mds# mount -t lustre -L testfs-MDT0000 /mnt/mdt
42 <para>Mount-by-label should NOT be used in a multi-path environment or
43 when snapshots are being created of the device, since multiple block
44 devices will have the same label.</para>
46 <para>Although the file system name is internally limited to 8 characters,
47 you can mount the clients at any mount point, so file system users are not
48 subjected to short names. Here is an example:</para>
50 client# mount -t lustre mds0@tcp0:/short
51 <replaceable>/dev/long_mountpoint_name</replaceable>
54 <section xml:id="dbdoclet.50438194_24122">
57 <primary>operations</primary>
58 <secondary>starting</secondary>
59 </indexterm>Starting Lustre</title>
60 <para>On the first start of a Lustre file system, the components must be
61 started in the following order:</para>
64 <para>Mount the MGT.</para>
66 <para>If a combined MGT/MDT is present, Lustre will correctly mount
67 the MGT and MDT automatically.</para>
71 <para>Mount the MDT.</para>
73 <para condition='l24'>Mount all MDTs if multiple MDTs are
78 <para>Mount the OST(s).</para>
81 <para>Mount the client(s).</para>
85 <section xml:id="dbdoclet.50438194_84876">
88 <primary>operations</primary>
89 <secondary>mounting</secondary>
90 </indexterm>Mounting a Server</title>
91 <para>Starting a Lustre server is straightforward and only involves the
92 mount command. Lustre servers can be added to
93 <literal>/etc/fstab</literal>:</para>
97 <para>The mount command generates output similar to this:</para>
99 /dev/sda1 on /mnt/test/mdt type lustre (rw)
100 /dev/sda2 on /mnt/test/ost0 type lustre (rw)
101 192.168.0.21@tcp:/testfs on /mnt/testfs type lustre (rw)
103 <para>In this example, the MDT, an OST (ost0) and file system (testfs) are
106 LABEL=testfs-MDT0000 /mnt/test/mdt lustre defaults,_netdev,noauto 0 0
107 LABEL=testfs-OST0000 /mnt/test/ost0 lustre defaults,_netdev,noauto 0 0
109 <para>In general, it is wise to specify noauto and let your
110 high-availability (HA) package manage when to mount the device. If you are
111 not using failover, make sure that networking has been started before
112 mounting a Lustre server. If you are running Red Hat Enterprise Linux, SUSE
113 Linux Enterprise Server, Debian operating system (and perhaps others), use
115 <literal>_netdev</literal> flag to ensure that these disks are mounted after
116 the network is up.</para>
117 <para>We are mounting by disk label here. The label of a device can be read
119 <literal>e2label</literal>. The label of a newly-formatted Lustre server
121 <literal>FFFF</literal> if the
122 <literal>--index</literal> option is not specified to
123 <literal>mkfs.lustre</literal>, meaning that it has yet to be assigned. The
124 assignment takes place when the server is first started, and the disk label
125 is updated. It is recommended that the
126 <literal>--index</literal> option always be used, which will also ensure
127 that the label is set at format time.</para>
129 <para>Do not do this when the client and OSS are on the same node, as
130 memory pressure between the client and OSS can lead to deadlocks.</para>
133 <para>Mount-by-label should NOT be used in a multi-path
137 <section xml:id="dbdoclet.50438194_69255">
140 <primary>operations</primary>
141 <secondary>unmounting</secondary>
142 </indexterm>Unmounting a Server</title>
143 <para>To stop a Lustre server, use the
145 <replaceable>/mount</replaceable>
146 <replaceable>point</replaceable></literal> command.</para>
147 <para>For example, to stop
148 <literal>ost0</literal> on mount point
149 <literal>/mnt/test</literal>, run:</para>
153 <para>Gracefully stopping a server with the
154 <literal>umount</literal> command preserves the state of the connected
155 clients. The next time the server is started, it waits for clients to
156 reconnect, and then goes through the recovery procedure.</para>
158 <literal>-f</literal>) flag is used, then the server evicts all clients and
159 stops WITHOUT recovery. Upon restart, the server does not wait for
160 recovery. Any currently connected clients receive I/O errors until they
163 <para>If you are using loopback devices, use the
164 <literal>-d</literal> flag. This flag cleans up loop devices and can
165 always be safely specified.</para>
168 <section xml:id="dbdoclet.50438194_57420">
171 <primary>operations</primary>
172 <secondary>failover</secondary>
173 </indexterm>Specifying Failout/Failover Mode for OSTs</title>
174 <para>In a Lustre file system, an OST that has become unreachable because
175 it fails, is taken off the network, or is unmounted can be handled in one
180 <literal>failout</literal> mode, Lustre clients immediately receive
181 errors (EIOs) after a timeout, instead of waiting for the OST to
186 <literal>failover</literal> mode, Lustre clients wait for the OST to
190 <para>By default, the Lustre file system uses
191 <literal>failover</literal> mode for OSTs. To specify
192 <literal>failout</literal> mode instead, use the
193 <literal>--param="failover.mode=failout"</literal> option as shown below
194 (entered on one line):</para>
196 oss# mkfs.lustre --fsname=
197 <replaceable>fsname</replaceable> --mgsnode=
198 <replaceable>mgs_NID</replaceable> --param=failover.mode=failout
200 <replaceable>ost_index</replaceable>
201 <replaceable>/dev/ost_block_device</replaceable>
203 <para>In the example below,
204 <literal>failout</literal> mode is specified for the OSTs on the MGS
205 <literal>mds0</literal> in the file system
206 <literal>testfs</literal>(entered on one line).</para>
208 oss# mkfs.lustre --fsname=testfs --mgsnode=mds0 --param=failover.mode=failout
209 --ost --index=3 /dev/sdb
212 <para>Before running this command, unmount all OSTs that will be affected
214 <literal>failover</literal>/
215 <literal>failout</literal> mode.</para>
218 <para>After initial file system configuration, use the
219 <literal>tunefs.lustre</literal> utility to change the mode. For example,
221 <literal>failout</literal> mode, run:</para>
224 $ tunefs.lustre --param failover.mode=failout
225 <replaceable>/dev/ost_device</replaceable>
230 <section xml:id="dbdoclet.50438194_54138">
233 <primary>operations</primary>
234 <secondary>degraded OST RAID</secondary>
235 </indexterm>Handling Degraded OST RAID Arrays</title>
236 <para>Lustre includes functionality that notifies Lustre if an external
237 RAID array has degraded performance (resulting in reduced overall file
238 system performance), either because a disk has failed and not been
239 replaced, or because a disk was replaced and is undergoing a rebuild. To
240 avoid a global performance slowdown due to a degraded OST, the MDS can
241 avoid the OST for new object allocation if it is notified of the degraded
243 <para>A parameter for each OST, called
244 <literal>degraded</literal>, specifies whether the OST is running in
245 degraded mode or not.</para>
246 <para>To mark the OST as degraded, use:</para>
248 lctl set_param obdfilter.{OST_name}.degraded=1
250 <para>To mark that the OST is back in normal operation, use:</para>
252 lctl set_param obdfilter.{OST_name}.degraded=0
254 <para>To determine if OSTs are currently in degraded mode, use:</para>
256 lctl get_param obdfilter.*.degraded
258 <para>If the OST is remounted due to a reboot or other condition, the flag
260 <literal>0</literal>.</para>
261 <para>It is recommended that this be implemented by an automated script
262 that monitors the status of individual RAID devices.</para>
264 <section xml:id="dbdoclet.50438194_88063">
267 <primary>operations</primary>
268 <secondary>multiple file systems</secondary>
269 </indexterm>Running Multiple Lustre File Systems</title>
270 <para>Lustre supports multiple file systems provided the combination of
271 <literal>NID:fsname</literal> is unique. Each file system must be allocated
272 a unique name during creation with the
273 <literal>--fsname</literal> parameter. Unique names for file systems are
274 enforced if a single MGS is present. If multiple MGSs are present (for
275 example if you have an MGS on every MDS) the administrator is responsible
276 for ensuring file system names are unique. A single MGS and unique file
277 system names provides a single point of administration and allows commands
278 to be issued against the file system even if it is not mounted.</para>
279 <para>Lustre supports multiple file systems on a single MGS. With a single
280 MGS fsnames are guaranteed to be unique. Lustre also allows multiple MGSs
281 to co-exist. For example, multiple MGSs will be necessary if multiple file
282 systems on different Lustre software versions are to be concurrently
283 available. With multiple MGSs additional care must be taken to ensure file
284 system names are unique. Each file system should have a unique fsname among
285 all systems that may interoperate in the future.</para>
286 <para>By default, the
287 <literal>mkfs.lustre</literal> command creates a file system named
288 <literal>lustre</literal>. To specify a different file system name (limited
289 to 8 characters) at format time, use the
290 <literal>--fsname</literal> option:</para>
293 mkfs.lustre --fsname=
294 <replaceable>file_system_name</replaceable>
298 <para>The MDT, OSTs and clients in the new file system must use the same
299 file system name (prepended to the device name). For example, for a new
301 <literal>foo</literal>, the MDT and two OSTs would be named
302 <literal>foo-MDT0000</literal>,
303 <literal>foo-OST0000</literal>, and
304 <literal>foo-OST0001</literal>.</para>
306 <para>To mount a client on the file system, run:</para>
308 client# mount -t lustre
309 <replaceable>mgsnode</replaceable>:
310 <replaceable>/new_fsname</replaceable>
311 <replaceable>/mount_point</replaceable>
313 <para>For example, to mount a client on file system foo at mount point
314 /mnt/foo, run:</para>
316 client# mount -t lustre mgsnode:/foo /mnt/foo
319 <para>If a client(s) will be mounted on several file systems, add the
321 <literal>/etc/xattr.conf</literal> file to avoid problems when files are
322 moved between the file systems:
323 <literal>lustre.* skip</literal></para>
326 <para>To ensure that a new MDT is added to an existing MGS create the MDT
328 <literal>--mdt --mgsnode=
329 <replaceable>mgs_NID</replaceable></literal>.</para>
331 <para>A Lustre installation with two file systems (
332 <literal>foo</literal> and
333 <literal>bar</literal>) could look like this, where the MGS node is
334 <literal>mgsnode@tcp0</literal> and the mount points are
335 <literal>/mnt/foo</literal> and
336 <literal>/mnt/bar</literal>.</para>
338 mgsnode# mkfs.lustre --mgs /dev/sda
339 mdtfoonode# mkfs.lustre --fsname=foo --mgsnode=mgsnode@tcp0 --mdt --index=0
341 ossfoonode# mkfs.lustre --fsname=foo --mgsnode=mgsnode@tcp0 --ost --index=0
343 ossfoonode# mkfs.lustre --fsname=foo --mgsnode=mgsnode@tcp0 --ost --index=1
345 mdtbarnode# mkfs.lustre --fsname=bar --mgsnode=mgsnode@tcp0 --mdt --index=0
347 ossbarnode# mkfs.lustre --fsname=bar --mgsnode=mgsnode@tcp0 --ost --index=0
349 ossbarnode# mkfs.lustre --fsname=bar --mgsnode=mgsnode@tcp0 --ost --index=1
352 <para>To mount a client on file system foo at mount point
353 <literal>/mnt/foo</literal>, run:</para>
355 client# mount -t lustre mgsnode@tcp0:/foo /mnt/foo
357 <para>To mount a client on file system bar at mount point
358 <literal>/mnt/bar</literal>, run:</para>
360 client# mount -t lustre mgsnode@tcp0:/bar /mnt/bar
363 <section xml:id="dbdoclet.lfsmkdir" condition='l24'>
366 <primary>operations</primary>
367 <secondary>remote directory</secondary>
368 </indexterm>Creating a sub-directory on a given MDT</title>
369 <para>Lustre 2.4 enables individual sub-directories to be serviced by
370 unique MDTs. An administrator can allocate a sub-directory to a given MDT
371 using the command:</para>
373 client# lfs mkdir –i
374 <replaceable>mdt_index</replaceable>
375 <replaceable>/mount_point/remote_dir</replaceable>
377 <para>This command will allocate the sub-directory
378 <literal>remote_dir</literal> onto the MDT of index
379 <literal>mdt_index</literal>. For more information on adding additional MDTs
381 <literal>mdt_index</literal> see
382 <xref linkend='dbdoclet.addmdtindex' />.</para>
384 <para>An administrator can allocate remote sub-directories to separate
385 MDTs. Creating remote sub-directories in parent directories not hosted on
386 MDT0 is not recommended. This is because the failure of the parent MDT
387 will leave the namespace below it inaccessible. For this reason, by
388 default it is only possible to create remote sub-directories off MDT0. To
389 relax this restriction and enable remote sub-directories off any MDT, an
390 administrator must issue the command
391 <literal>lctl set_param mdt.*.enable_remote_dir=1</literal>.</para>
393 <para condition='l28'>With Lustre software version 2.8, a new
394 tunable is available to allow users with a specific group ID to create
395 and delete remote and striped directories. This tunable is
396 <literal>enable_remote_dir_gid</literal>. For example, setting this
397 parameter to the 'wheel' or 'admin' group ID allows users with that GID
398 to create and delete remote and striped directories. Setting this
399 parameter to <literal>-1</literal> on MDT0 to permanently allow any
400 non-root users create and delete remote and striped directories. For
402 <screen>lctl set_param -P mdt.*.enable_remote_dir_gid=-1</screen>
405 <section xml:id="dbdoclet.lfsmkdirdne2" condition='l28'>
408 <primary>operations</primary>
409 <secondary>striped directory</secondary>
412 <primary>operations</primary>
413 <secondary>mkdir</secondary>
416 <primary>operations</primary>
417 <secondary>setdirstripe</secondary>
420 <primary>striping</primary>
421 <secondary>metadata</secondary>
422 </indexterm>Creating a directory striped across multiple MDTs</title>
423 <para>The Lustre 2.8 DNE feature enables individual files in a given
424 directory to store their metadata on separate MDTs (a <emphasis>striped
425 directory</emphasis>) once additional MDTs have been added to the
426 filesystem, see <xref linkend="dbdoclet.addingamdt"/>.
427 The result of this is that metadata requests for
428 files in a striped directory are serviced by multiple MDTs and metadata
429 service load is distributed over all the MDTs that service a given
430 directory. By distributing metadata service load over multiple MDTs,
431 performance can be improved beyond the limit of single MDT
432 performance. Prior to the development of this feature all files in a
433 directory must record their metadata on a single MDT.</para>
434 <para>This command to stripe a directory over
435 <replaceable>mdt_count</replaceable> MDTs is:
439 <replaceable>mdt_count</replaceable>
440 <replaceable>/mount_point/new_directory</replaceable>
442 <para>The striped directory feature is most useful for distributing
443 single large directories (50k entries or more) across multiple MDTs,
444 since it incurs more overhead than non-striped directories.</para>
446 <section xml:id="dbdoclet.50438194_88980">
449 <primary>operations</primary>
450 <secondary>parameters</secondary>
451 </indexterm>Setting and Retrieving Lustre Parameters</title>
452 <para>Several options are available for setting parameters in
456 <para>When creating a file system, use mkfs.lustre. See
457 <xref linkend="dbdoclet.50438194_17237" />below.</para>
460 <para>When a server is stopped, use tunefs.lustre. See
461 <xref linkend="dbdoclet.50438194_55253" />below.</para>
464 <para>When the file system is running, use lctl to set or retrieve
465 Lustre parameters. See
466 <xref linkend="dbdoclet.50438194_51490" />and
467 <xref linkend="dbdoclet.50438194_63247" />below.</para>
470 <section xml:id="dbdoclet.50438194_17237">
471 <title>Setting Tunable Parameters with
472 <literal>mkfs.lustre</literal></title>
473 <para>When the file system is first formatted, parameters can simply be
475 <literal>--param</literal> option to the
476 <literal>mkfs.lustre</literal> command. For example:</para>
478 mds# mkfs.lustre --mdt --param="sys.timeout=50" /dev/sda
480 <para>For more details about creating a file system,see
481 <xref linkend="configuringlustre" />. For more details about
482 <literal>mkfs.lustre</literal>, see
483 <xref linkend="systemconfigurationutilities" />.</para>
485 <section xml:id="dbdoclet.50438194_55253">
486 <title>Setting Parameters with
487 <literal>tunefs.lustre</literal></title>
488 <para>If a server (OSS or MDS) is stopped, parameters can be added to an
489 existing file system using the
490 <literal>--param</literal> option to the
491 <literal>tunefs.lustre</literal> command. For example:</para>
493 oss# tunefs.lustre --param=failover.node=192.168.0.13@tcp0 /dev/sda
496 <literal>tunefs.lustre</literal>, parameters are
497 <emphasis>additive</emphasis>-- new parameters are specified in addition
498 to old parameters, they do not replace them. To erase all old
499 <literal>tunefs.lustre</literal> parameters and just use newly-specified
500 parameters, run:</para>
502 mds# tunefs.lustre --erase-params --param=
503 <replaceable>new_parameters</replaceable>
505 <para>The tunefs.lustre command can be used to set any parameter settable
506 in a /proc/fs/lustre file and that has its own OBD device, so it can be
509 <replaceable>obdname|fsname</replaceable>.
510 <replaceable>obdtype</replaceable>.
511 <replaceable>proc_file_name</replaceable>=
512 <replaceable>value</replaceable></literal>. For example:</para>
514 mds# tunefs.lustre --param mdt.identity_upcall=NONE /dev/sda1
516 <para>For more details about
517 <literal>tunefs.lustre</literal>, see
518 <xref linkend="systemconfigurationutilities" />.</para>
520 <section xml:id="dbdoclet.50438194_51490">
521 <title>Setting Parameters with
522 <literal>lctl</literal></title>
523 <para>When the file system is running, the
524 <literal>lctl</literal> command can be used to set parameters (temporary
525 or permanent) and report current parameter values. Temporary parameters
526 are active as long as the server or client is not shut down. Permanent
527 parameters live through server and client reboots.</para>
529 <para>The lctl list_param command enables users to list all parameters
531 <xref linkend="dbdoclet.50438194_88217" />.</para>
533 <para>For more details about the
534 <literal>lctl</literal> command, see the examples in the sections below
536 <xref linkend="systemconfigurationutilities" />.</para>
538 <title>Setting Temporary Parameters</title>
540 <literal>lctl set_param</literal> to set temporary parameters on the
541 node where it is run. These parameters map to items in
542 <literal>/proc/{fs,sys}/{lnet,lustre}</literal>. The
543 <literal>lctl set_param</literal> command uses this syntax:</para>
546 <replaceable>obdtype</replaceable>.
547 <replaceable>obdname</replaceable>.
548 <replaceable>proc_file_name</replaceable>=
549 <replaceable>value</replaceable>
551 <para>For example:</para>
553 # lctl set_param osc.*.max_dirty_mb=1024
554 osc.myth-OST0000-osc.max_dirty_mb=32
555 osc.myth-OST0001-osc.max_dirty_mb=32
556 osc.myth-OST0002-osc.max_dirty_mb=32
557 osc.myth-OST0003-osc.max_dirty_mb=32
558 osc.myth-OST0004-osc.max_dirty_mb=32
561 <section xml:id="dbdoclet.50438194_64195">
562 <title>Setting Permanent Parameters</title>
564 <literal>lctl conf_param</literal> command to set permanent parameters.
566 <literal>lctl conf_param</literal> command can be used to specify any
567 parameter settable in a
568 <literal>/proc/fs/lustre</literal> file, with its own OBD device. The
569 <literal>lctl conf_param</literal> command uses this syntax (same as the
571 <literal>mkfs.lustre</literal> and
572 <literal>tunefs.lustre</literal> commands):</para>
574 <replaceable>obdname|fsname</replaceable>.
575 <replaceable>obdtype</replaceable>.
576 <replaceable>proc_file_name</replaceable>=
577 <replaceable>value</replaceable>)
579 <para>Here are a few examples of
580 <literal>lctl conf_param</literal> commands:</para>
582 mgs# lctl conf_param testfs-MDT0000.sys.timeout=40
583 $ lctl conf_param testfs-MDT0000.mdt.identity_upcall=NONE
584 $ lctl conf_param testfs.llite.max_read_ahead_mb=16
585 $ lctl conf_param testfs-MDT0000.lov.stripesize=2M
586 $ lctl conf_param testfs-OST0000.osc.max_dirty_mb=29.15
587 $ lctl conf_param testfs-OST0000.ost.client_cache_seconds=15
588 $ lctl conf_param testfs.sys.timeout=40
591 <para>Parameters specified with the
592 <literal>lctl conf_param</literal> command are set permanently in the
593 file system's configuration file on the MGS.</para>
596 <section xml:id="dbdoclet.setparamp" condition='l25'>
597 <title>Setting Permanent Parameters with lctl set_param -P</title>
599 <literal>lctl set_param -P</literal> to set parameters permanently. This
600 command must be issued on the MGS. The given parameter is set on every
602 <literal>lctl</literal> upcall. Parameters map to items in
603 <literal>/proc/{fs,sys}/{lnet,lustre}</literal>. The
604 <literal>lctl set_param</literal> command uses this syntax:</para>
607 <replaceable>obdtype</replaceable>.
608 <replaceable>obdname</replaceable>.
609 <replaceable>proc_file_name</replaceable>=
610 <replaceable>value</replaceable>
612 <para>For example:</para>
614 # lctl set_param -P osc.*.max_dirty_mb=1024
615 osc.myth-OST0000-osc.max_dirty_mb=32
616 osc.myth-OST0001-osc.max_dirty_mb=32
617 osc.myth-OST0002-osc.max_dirty_mb=32
618 osc.myth-OST0003-osc.max_dirty_mb=32
619 osc.myth-OST0004-osc.max_dirty_mb=32
622 <literal>-d</literal>(only with -P) option to delete permanent
623 parameter. Syntax:</para>
626 <replaceable>obdtype</replaceable>.
627 <replaceable>obdname</replaceable>.
628 <replaceable>proc_file_name</replaceable>
630 <para>For example:</para>
632 # lctl set_param -P -d osc.*.max_dirty_mb
635 <section xml:id="dbdoclet.50438194_88217">
636 <title>Listing Parameters</title>
637 <para>To list Lustre or LNET parameters that are available to set, use
639 <literal>lctl list_param</literal> command. For example:</para>
641 lctl list_param [-FR]
642 <replaceable>obdtype</replaceable>.
643 <replaceable>obdname</replaceable>
645 <para>The following arguments are available for the
646 <literal>lctl list_param</literal> command.</para>
648 <literal>-F</literal> Add '
649 <literal>/</literal>', '
650 <literal>@</literal>' or '
651 <literal>=</literal>' for directories, symlinks and writeable files,
654 <literal>-R</literal> Recursively lists all parameters under the
655 specified path</para>
656 <para>For example:</para>
658 oss# lctl list_param obdfilter.lustre-OST0000
661 <section xml:id="dbdoclet.50438194_63247">
662 <title>Reporting Current Parameter Values</title>
663 <para>To report current Lustre parameter values, use the
664 <literal>lctl get_param</literal> command with this syntax:</para>
667 <replaceable>obdtype</replaceable>.
668 <replaceable>obdname</replaceable>.
669 <replaceable>proc_file_name</replaceable>
671 <para>This example reports data on RPC service times.</para>
673 oss# lctl get_param -n ost.*.ost_io.timeouts
674 service : cur 1 worst 30 (at 1257150393, 85d23h58m54s ago) 1 1 1 1
676 <para>This example reports the amount of space this client has reserved
677 for writeback cache with each OST:</para>
679 client# lctl get_param osc.*.cur_grant_bytes
680 osc.myth-OST0000-osc-ffff8800376bdc00.cur_grant_bytes=2097152
681 osc.myth-OST0001-osc-ffff8800376bdc00.cur_grant_bytes=33890304
682 osc.myth-OST0002-osc-ffff8800376bdc00.cur_grant_bytes=35418112
683 osc.myth-OST0003-osc-ffff8800376bdc00.cur_grant_bytes=2097152
684 osc.myth-OST0004-osc-ffff8800376bdc00.cur_grant_bytes=33808384
689 <section xml:id="dbdoclet.50438194_41817">
692 <primary>operations</primary>
693 <secondary>failover</secondary>
694 </indexterm>Specifying NIDs and Failover</title>
695 <para>If a node has multiple network interfaces, it may have multiple NIDs,
696 which must all be identified so other nodes can choose the NID that is
697 appropriate for their network interfaces. Typically, NIDs are specified in
698 a list delimited by commas (
699 <literal>,</literal>). However, when failover nodes are specified, the NIDs
700 are delimited by a colon (
701 <literal>:</literal>) or by repeating a keyword such as
702 <literal>--mgsnode=</literal> or
703 <literal>--servicenode=</literal>).</para>
704 <para>To display the NIDs of all servers in networks configured to work
705 with the Lustre file system, run (while LNET is running):</para>
709 <para>In the example below,
710 <literal>mds0</literal> and
711 <literal>mds1</literal> are configured as a combined MGS/MDT failover pair
713 <literal>oss0</literal> and
714 <literal>oss1</literal> are configured as an OST failover pair. The Ethernet
716 <literal>mds0</literal> is 192.168.10.1, and for
717 <literal>mds1</literal> is 192.168.10.2. The Ethernet addresses for
718 <literal>oss0</literal> and
719 <literal>oss1</literal> are 192.168.10.20 and 192.168.10.21
722 mds0# mkfs.lustre --fsname=testfs --mdt --mgs \
723 --servicenode=192.168.10.2@tcp0 \
724 -–servicenode=192.168.10.1@tcp0 /dev/sda1
725 mds0# mount -t lustre /dev/sda1 /mnt/test/mdt
726 oss0# mkfs.lustre --fsname=testfs --servicenode=192.168.10.20@tcp0 \
727 --servicenode=192.168.10.21 --ost --index=0 \
728 --mgsnode=192.168.10.1@tcp0 --mgsnode=192.168.10.2@tcp0 \
730 oss0# mount -t lustre /dev/sdb /mnt/test/ost0
731 client# mount -t lustre 192.168.10.1@tcp0:192.168.10.2@tcp0:/testfs \
733 mds0# umount /mnt/mdt
734 mds1# mount -t lustre /dev/sda1 /mnt/test/mdt
735 mds1# lctl get_param mdt.testfs-MDT0000.recovery_status
737 <para>Where multiple NIDs are specified separated by commas (for example,
738 <literal>10.67.73.200@tcp,192.168.10.1@tcp</literal>), the two NIDs refer
739 to the same host, and the Lustre software chooses the
740 <emphasis>best</emphasis>one for communication. When a pair of NIDs is
741 separated by a colon (for example,
742 <literal>10.67.73.200@tcp:10.67.73.201@tcp</literal>), the two NIDs refer
743 to two different hosts and are treated as a failover pair (the Lustre
744 software tries the first one, and if that fails, it tries the second
747 <literal>mkfs.lustre</literal> can be used to specify failover nodes.
748 Introduced in Lustre software release 2.0, the
749 <literal>--servicenode</literal> option is used to specify all service NIDs,
750 including those for primary nodes and failover nodes. When the
751 <literal>--servicenode</literal> option is used, the first service node to
752 load the target device becomes the primary service node, while nodes
753 corresponding to the other specified NIDs become failover locations for the
754 target device. An older option,
755 <literal>--failnode</literal>, specifies just the NIDS of failover nodes.
756 For more information about the
757 <literal>--servicenode</literal> and
758 <literal>--failnode</literal> options, see
759 <xref xmlns:xlink="http://www.w3.org/1999/xlink"
760 linkend="configuringfailover" />.</para>
762 <section xml:id="dbdoclet.50438194_70905">
765 <primary>operations</primary>
766 <secondary>erasing a file system</secondary>
767 </indexterm>Erasing a File System</title>
768 <para>If you want to erase a file system and permanently delete all the
769 data in the file system, run this command on your targets:</para>
771 $ "mkfs.lustre --reformat"
773 <para>If you are using a separate MGS and want to keep other file systems
774 defined on that MGS, then set the
775 <literal>writeconf</literal> flag on the MDT for that file system. The
776 <literal>writeconf</literal> flag causes the configuration logs to be
777 erased; they are regenerated the next time the servers start.</para>
779 <literal>writeconf</literal> flag on the MDT:</para>
782 <para>Unmount all clients/servers using this file system, run:</para>
788 <para>Permanently erase the file system and, presumably, replace it
789 with another file system, run:</para>
791 $ mkfs.lustre --reformat --fsname spfs --mgs --mdt --index=0 /dev/
792 <emphasis>{mdsdev}</emphasis>
796 <para>If you have a separate MGS (that you do not want to reformat),
798 <literal>--writeconf</literal> flag to
799 <literal>mkfs.lustre</literal> on the MDT, run:</para>
801 $ mkfs.lustre --reformat --writeconf --fsname spfs --mgsnode=
802 <replaceable>mgs_nid</replaceable> --mdt --index=0
803 <replaceable>/dev/mds_device</replaceable>
808 <para>If you have a combined MGS/MDT, reformatting the MDT reformats the
809 MGS as well, causing all configuration information to be lost; you can
810 start building your new file system. Nothing needs to be done with old
811 disks that will not be part of the new file system, just do not mount
815 <section xml:id="dbdoclet.50438194_16954">
818 <primary>operations</primary>
819 <secondary>reclaiming space</secondary>
820 </indexterm>Reclaiming Reserved Disk Space</title>
821 <para>All current Lustre installations run the ldiskfs file system
822 internally on service nodes. By default, ldiskfs reserves 5% of the disk
823 space to avoid file system fragmentation. In order to reclaim this space,
824 run the following command on your OSS for each OST in the file
827 tune2fs [-m reserved_blocks_percent] /dev/
828 <emphasis>{ostdev}</emphasis>
830 <para>You do not need to shut down Lustre before running this command or
831 restart it afterwards.</para>
833 <para>Reducing the space reservation can cause severe performance
834 degradation as the OST file system becomes more than 95% full, due to
835 difficulty in locating large areas of contiguous free space. This
836 performance degradation may persist even if the space usage drops below
837 95% again. It is recommended NOT to reduce the reserved disk space below
841 <section xml:id="dbdoclet.50438194_69998">
844 <primary>operations</primary>
845 <secondary>replacing an OST or MDS</secondary>
846 </indexterm>Replacing an Existing OST or MDT</title>
847 <para>To copy the contents of an existing OST to a new OST (or an old MDT
848 to a new MDT), follow the process for either OST/MDT backups in
849 <xref linkend='dbdoclet.50438207_71633' />or
850 <xref linkend='dbdoclet.50438207_21638' />. For more information on
852 <xref linkend='dbdoclet.rmremotedir' />.</para>
854 <section xml:id="dbdoclet.50438194_30872">
857 <primary>operations</primary>
858 <secondary>identifying OSTs</secondary>
859 </indexterm>Identifying To Which Lustre File an OST Object Belongs</title>
860 <para>Use this procedure to identify the file containing a given object on
864 <para>On the OST (as root), run
865 <literal>debugfs</literal> to display the file identifier (
866 <literal>FID</literal>) of the file associated with the object.</para>
867 <para>For example, if the object is
868 <literal>34976</literal> on
869 <literal>/dev/lustre/ost_test2</literal>, the debug command is:
871 # debugfs -c -R "stat /O/0/d$((34976 % 32))/34976" /dev/lustre/ost_test2
873 <para>The command output is:
875 debugfs 1.42.3.wc3 (15-Aug-2012)
876 /dev/lustre/ost_test2: catastrophic mode - not reading inode or group bitmaps
877 Inode: 352365 Type: regular Mode: 0666 Flags: 0x80000
878 Generation: 2393149953 Version: 0x0000002a:00005f81
879 User: 1000 Group: 1000 Size: 260096
880 File ACL: 0 Directory ACL: 0
881 Links: 1 Blockcount: 512
882 Fragment: Address: 0 Number: 0 Size: 0
883 ctime: 0x4a216b48:00000000 -- Sat May 30 13:22:16 2009
884 atime: 0x4a216b48:00000000 -- Sat May 30 13:22:16 2009
885 mtime: 0x4a216b48:00000000 -- Sat May 30 13:22:16 2009
886 crtime: 0x4a216b3c:975870dc -- Sat May 30 13:22:04 2009
887 Size of extra inode fields: 24
888 Extended attributes stored in inode body:
889 fid = "b9 da 24 00 00 00 00 00 6a fa 0d 3f 01 00 00 00 eb 5b 0b 00 00 00 0000
890 00 00 00 00 00 00 00 00 " (32)
891 fid: objid=34976 seq=0 parent=[0x24dab9:0x3f0dfa6a:0x0] stripe=1
893 (0-64):4620544-4620607
897 <para>For Lustre software release 2.x file systems, the parent FID will
898 be of the form [0x200000400:0x122:0x0] and can be resolved directly
900 <literal>lfs fid2path [0x200000404:0x122:0x0]
901 /mnt/lustre</literal> command on any Lustre client, and the process is
905 <para>In this example the parent inode FID is an upgraded 1.x inode
906 (due to the first part of the FID being below 0x200000400), the MDT
908 <literal>0x24dab9</literal> and generation
909 <literal>0x3f0dfa6a</literal> and the pathname needs to be resolved
911 <literal>debugfs</literal>.</para>
914 <para>On the MDS (as root), use
915 <literal>debugfs</literal> to find the file associated with the
918 # debugfs -c -R "ncheck 0x24dab9" /dev/lustre/mdt_test
920 <para>Here is the command output:</para>
922 debugfs 1.42.3.wc2 (15-Aug-2012)
923 /dev/lustre/mdt_test: catastrophic mode - not reading inode or group bitmap\
926 2415289 /ROOT/brian-laptop-guest/clients/client11/~dmtmp/PWRPNT/ZD16.BMP
930 <para>The command lists the inode and pathname associated with the
934 <literal>Debugfs</literal>' ''ncheck'' is a brute-force search that may
935 take a long time to complete.</para>
938 <para>To find the Lustre file from a disk LBA, follow the steps listed in
939 the document at this URL:
940 <link xl:href="http://smartmontools.sourceforge.net/badblockhowto.html">
941 http://smartmontools.sourceforge.net/badblockhowto.html</link>. Then,
942 follow the steps above to resolve the Lustre filename.</para>