1mount.gfs2(8)               System Manager's Manual              mount.gfs2(8)
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NAME

6       mount.gfs2 - GFS2 mount options
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SYNOPSIS

10       mount -a [-fnrsvw] -t gfs2 [-O options]
11       mount [-fnrsvw] -t gfs2 [-o options ] device dir
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DESCRIPTION

15       For  details  on the common mount options, please see the mount(8) com‐
16       mand man page.  The device may be any block device on  which  you  have
17       created  a  GFS2  filesystem.  Examples include a single disk partition
18       (e.g. /dev/sdb3), a loopback device, a  device  exported  from  another
19       node  (e.g.  an iSCSI device), or a logical volume (typically comprised
20       of a number of individual disks).
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22       device does not necessarily need to match the device name  as  seen  on
23       another  node  in the cluster, nor does it need to be a logical volume.
24       However, the use of a cluster-aware volume manager such as  CLVM2  (see
25       lvm(8))  will  guarantee that the managed devices are named identically
26       on each node in a cluster (for much easier management), and will  allow
27       you  to configure a very large volume from multiple storage units (e.g.
28       disk drives).
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30       device must make the entire filesystem storage area visible to the com‐
31       puter.   That is, you cannot mount different parts of a single filesys‐
32       tem on different computers.  Each computer must see an entire  filesys‐
33       tem.   You  may, however, mount several GFS2 filesystems if you want to
34       distribute your data storage in a controllable way.
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36       This man page describes GFS2-specific options that can be passed to the
37       GFS2  file  system  at  mount  time, using the -o flag.  There are many
38       other -o options handled by the generic mount command  mount(8).   How‐
39       ever,  the  options  described below are specifically for GFS2, and are
40       not interpreted by the mount command nor by the kernel's  Virtual  File
41       System.   GFS2  and  non-GFS2 options may be intermingled after the -o,
42       separated by commas (but no spaces).
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44       The options commit,  discard,  errors,  quota_quantum,  statfs_quantum,
45       statfs_percent,  barrier,  acl, quota, suiddir, and data can be changed
46       after mount using the "mount -o  remount,option  /mountpoint"  command.
47       The  options quota, discard, barrier, acl, and suiddir support the "no"
48       prefix.  For example, "noacl" turns off what "acl" turns on.
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50       If you have trouble mounting GFS2, check the syslog (e.g. /var/log/mes‐
51       sages) for specific error messages.
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OPTIONS

55       lockproto=LockProtoName
56              This  specifies  which  inter-node  lock protocol is used by the
57              GFS2 filesystem for this mount, overriding the default lock pro‐
58              tocol name stored in the filesystem's on-disk superblock.
59
60              The  LockProtoName  must  be one of the supported locking proto‐
61              cols, currently these are lock_nolock and lock_dlm.
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63              The default lock protocol name is written to disk initially when
64              creating the filesystem with mkfs.gfs2(8), -p option.  It can be
65              changed on-disk by using the  gfs2_tool(8)  utility's  sb  proto
66              command.
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68              The  lockproto  mount  option  should be used only under special
69              circumstances in which you want to temporarily use  a  different
70              lock  protocol  without  changing the on-disk default. Using the
71              incorrect lock protocol on a  cluster  filesystem  mounted  from
72              more  than  one  node will almost certainly result in filesystem
73              corruption.
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75       locktable=LockTableName
76              This specifies the identity of the cluster and of the filesystem
77              for  this mount, overriding the default cluster/filesystem iden‐
78              tify stored in the filesystem's on-disk superblock.   The  clus‐
79              ter/filesystem  name is recognized globally throughout the clus‐
80              ter, and establishes a unique namespace for the inter-node lock‐
81              ing system, enabling the mounting of multiple GFS2 filesystems.
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83              The   format  of  LockTableName  is  lock-module-specific.   For
84              lock_dlm, the format is  clustername:fsname.   For  lock_nolock,
85              the field is ignored.
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87              The default cluster/filesystem name is written to disk initially
88              when creating the filesystem with mkfs.gfs2(8), -t  option.   It
89              can  be  changed  on-disk by using the gfs2_tool(8) utility's sb
90              table command.
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92              The locktable mount option should be  used  only  under  special
93              circumstances  in  which  you  want to mount the filesystem in a
94              different cluster, or mount it as a different  filesystem  name,
95              without changing the on-disk default.
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97       localcaching
98              This  flag  tells  GFS2 that it is running as a local (not clus‐
99              tered) filesystem, so it can turn on some  block  caching  opti‐
100              mizations that can't be used when running in cluster mode.
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102              This  is  turned on automatically by the lock_nolock module, but
103              can be overridden by using the ignore_local_fs option.
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105       localflocks
106              This flag tells GFS2 that it is running as a  local  (not  clus‐
107              tered)  filesystem,  so  it can allow the kernel VFS layer to do
108              all flock and fcntl file locking.  When running in cluster mode,
109              these  file locks require inter-node locks, and require the sup‐
110              port of GFS2.   When  running  locally,  better  performance  is
111              achieved by letting VFS handle the whole job.
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113              This  is  turned on automatically by the lock_nolock module, but
114              can be overridden by using the ignore_local_fs option.
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116       errors=[panic|withdraw]
117              Setting errors=panic causes GFS2 to oops  when  encountering  an
118              error  that would otherwise cause the mount to withdraw or print
119              an assertion warning. The default  setting  is  errors=withdraw.
120              This  option  should  not  be  used  in a production system.  It
121              replaces the earlier debug option on kernel versions 2.6.31  and
122              above.
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124       ignore_local_fs
125              By  default, using the nolock lock module automatically turns on
126              the localcaching and localflocks optimizations.  ignore_local_fs
127              forces  GFS2  to  treat the filesystem as if it were a multihost
128              (clustered) filesystem, with localcaching and localflocks  opti‐
129              mizations turned off.
130
131       upgrade
132              This  flag tells GFS2 to upgrade the filesystem's on-disk format
133              to the version supported by the current GFS2 software  installa‐
134              tion  on this computer.  If you try to mount an old-version disk
135              image, GFS2 will notify you via a syslog message that  you  need
136              to  upgrade.   Try  mounting again, using the -o upgrade option.
137              When upgrading, only one node may mount the GFS2 filesystem.
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139       acl    Enables POSIX Access Control List acl(5) support within GFS2.
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141       spectator
142              Mount this filesystem using a special form of  read-only  mount.
143              The  mount  does  not  use one of the filesystem's journals. The
144              node is unable to recover journals for other nodes.
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146       suiddir
147              Sets owner of any newly created file or directory to be that  of
148              parent  directory,  if  parent  directory has S_ISUID permission
149              attribute bit set.  Sets S_ISUID in any new  directory,  if  its
150              parent directory's S_ISUID is set.  Strips all execution bits on
151              a new file, if parent directory owner is different from owner of
152              process creating the file.  Set this option only if you know why
153              you are setting it.
154
155       quota=[off/account/on]
156              Turns quotas on or off for a filesystem.  Setting the quotas  to
157              be  in  the "account" state causes the per UID/GID usage statis‐
158              tics to be correctly maintained by  the  filesystem,  limit  and
159              warn values are ignored.  The default value is "off".
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161       discard
162              Causes  GFS2 to generate "discard" I/O requests for blocks which
163              have been freed. These can  be  used  by  suitable  hardware  to
164              implement thin-provisioning and similar schemes. This feature is
165              supported in kernel version 2.6.30 and above.
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167       barrier
168              This option, which defaults to on, causes GFS2 to send I/O  bar‐
169              riers  when  flushing  the  journal. The option is automatically
170              turned off if the underlying device does not support I/O  barri‐
171              ers.  We  highly  recommend the use of I/O barriers with GFS2 at
172              all times unless the block device is designed so that it  cannot
173              lose  its  write cache content (e.g. its on a UPS, or it doesn't
174              have a write cache)
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176       commit=secs
177              This is similar to the ext3 commit= option in that it  sets  the
178              maximum  number  of  seconds between journal commits if there is
179              dirty data in the journal.  The  default  is  60  seconds.  This
180              option is only provided in kernel versions 2.6.31 and above.
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182       data=[ordered|writeback]
183              When  data=ordered  is set, the user data modified by a transac‐
184              tion is flushed to the disk before the transaction is  committed
185              to disk.  This should prevent the user from seeing uninitialized
186              blocks in a file after a crash.  Data=writeback mode writes  the
187              user  data  to  the  disk  at any time after it's dirtied.  This
188              doesn't provide the same consistency guarantee as ordered  mode,
189              but  it  should  be  slightly  faster  for  some workloads.  The
190              default is ordered mode.
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192       meta   This option results in selecting the meta filesystem root rather
193              than  the  normal  filesystem root. This option is normally only
194              used by the GFS2 utility functions. Altering  any  file  on  the
195              GFS2 meta filesystem may render the filesystem unusable, so only
196              experts in the GFS2 on-disk layout should use this option.
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198       quota_quantum=secs
199              This sets the number of seconds for which a change in the  quota
200              information  may  sit  on  one  node before being written to the
201              quota file. This is the preferred way to set this parameter. The
202              value  is  an  integer  number of seconds greater than zero. The
203              default is 60 seconds. Shorter settings result in faster updates
204              of  the  lazy  quota  information and less likelihood of someone
205              exceeding their quota. Longer settings  make  filesystem  opera‐
206              tions involving quotas faster and more efficient.
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208       statfs_quantum=secs
209              Setting statfs_quantum to 0 is the preferred way to set the slow
210              version of statfs. The default value is 30 secs which  sets  the
211              maximum  time  period before statfs changes will be syned to the
212              master statfs file.  This can be adjusted to allow  for  faster,
213              less accurate statfs values or slower more accurate values. When
214              set to 0, statfs will always report the true values.
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216       statfs_percent=value
217              This setting provides a bound on the maximum  percentage  change
218              in  the  statfs information on a local basis before it is synced
219              back to the master statfs file, even if the time period has  not
220              expired.  If  the setting of statfs_quantum is 0, then this set‐
221              ting is ignored.
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BUGS

225       GFS2 doesn't support errors=remount-ro or data=journal.  It is not pos‐
226       sible  to  switch support for user and group quotas on and off indepen‐
227       dently of each other. Some of the error messages are rather cryptic, if
228       you  encounter one of these messages check firstly that gfs_controld is
229       running and secondly that you have enough journals  on  the  filesystem
230       for the number of nodes in use.
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SEE ALSO

234       gfs2(5),  mount(8) for general mount options, chmod(1) and chmod(2) for
235       access permission flags, acl(5) for access control  lists,  lvm(8)  for
236       volume management, ccs(7) for cluster management, umount(8), initrd(4).
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