1MOUNT.NILFS2(8)             System Manager's Manual            MOUNT.NILFS2(8)
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NAME

6       mount.nilfs2 - mount a NILFS2 file system
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SYNOPSIS

9       mount -t nilfs2 [-finrvw] [-o options [,...]] device dir
10       mount -t nilfs2 [-finrvw] [-o options [,...]] device | dir
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12       mount.nilfs2 [-fnrvw] [-o options [,...]] device dir
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14       mount.nilfs2 [-V]
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DESCRIPTION

17       mount.nilfs2  serves  to  attach  a NILFS2 file system on the specified
18       directory dir. It is intended to be executed from  mount(8),  and  will
19       invoke  the  garbage  collector nilfs_cleanerd(8) after an actual mount
20       system call has succeeded.  Conversely, umount.nilfs2(8) will  shutdown
21       the garbage collector before detaching the file system.
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23       The standard command line interface is the first form:
24              mount -t nilfs2 [options] device dir
25       This tells the kernel to attach the NILFS2 file system on device at the
26       directory dir.  With the second form, the mount program tries  to  find
27       out a missing device or dir argument from the /etc/fstab table.
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29       The  third  form,  which  directly invokes mount.nilfs2, is also usable
30       since mount.nilfs2 maintains by itself the system mount state  such  as
31       the  list  of mounted file systems described in /etc/mtab. However, the
32       first or the second form is usually recommended because some  expansive
33       options are not supported by the third form.
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OPTIONS

36       The full set of options used by an invocation of mount(8) is determined
37       by extracting the options from  the  fstab  table,  then  applying  any
38       options  specified  by the -o argument, and finally applying a -r or -w
39       option, when present.
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41       See mount(8) for the full set of options.  Commonly used options are as
42       follows:
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44       -V     Output version.
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46       -f     Fakes  mounting  the file system, meaning that the actual system
47              call will be skipped.  This option is used to  add  entries  for
48              devices  that  were  mounted  earlier with the -n option. It can
49              also be used for invoking nilfs_cleanerd(8) skipped previously.
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51       -i     Don't call mount.nilfs2.  This disables garbage  collection  and
52              handling of pseudo mount options.
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54       -n     Mount without writing in /etc/mtab.  This is necessary for exam‐
55              ple when /etc is on a read-only file system.
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57       -r     Mount the file system read-only.  A synonym is "-o ro".
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59       -v     Verbose mode.
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61       -w     Mount the file system read/write. This is the default. A synonym
62              is "-o rw".
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64       -o     Options  are  specified with a -o flag followed by a comma sepa‐
65              rated string of options.  Some of these options are only  useful
66              when  they appear in the /etc/fstab file.  For standard filesys‐
67              tem options, see mount(8).
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NILFS2 SPECIFIC MOUNT OPTIONS

70       The following options apply only to the NILFS2  filesystem.   They  all
71       follow the -o flag.
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73       barrier / nobarrier
74              These options enable/disable (default is enabled) barrier writes
75              for the block I/O to a lower device.  The barrier  write  serves
76              an  important  role to ensure consistency of filesystems after a
77              system crash or power failure.   NILFS2  uses  this  feature  by
78              default  to  assure the reliability.  For devices not supporting
79              the barrier write, it will be disabled automatically and a warn‐
80              ing will be logged.
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82       cp=checkpoint-number
83              Specify  the  checkpoint-number  of  the snapshot to be mounted.
84              Checkpoints and snapshots  are  listed  by  lscp(1).   Only  the
85              checkpoints  marked  as snapshot are mountable with this option.
86              Note that the read-only mount option must be specified together.
87
88       errors=continue / errors=remount-ro / errors=panic
89              Define the behaviour when  an  error  is  encountered.   (Either
90              ignore  errors  and just mark the file system erroneous and con‐
91              tinue, or remount the file system read-only, or panic  and  halt
92              the  system.)   The  default  is remount-ro.  In earlier kernels
93              than Linux 2.6.35, continue was the default.
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95       pp=protection-period
96              Specify the protection-period for the cleaner  daemon  (in  sec‐
97              onds).  nilfs_cleanerd  never  deletes  recent checkpoints whose
98              elapsed time from  its  creation  is  smaller  than  protection-
99              period.
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101       nogc   Disable  garbage  collection.  The  cleaner  daemon  will not be
102              started.  It can be be started manually, but  in  that  case  it
103              must also be stopped manually before unmounting.
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105       order=relaxed / order=strict
106              Specify order semantics for file data.  Metadata is always writ‐
107              ten to follow the POSIX semantics about the order of  filesystem
108              operations.
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110              relaxed
111                     Apply  relaxed  order semantics that allows modified data
112                     blocks to be written to disk without making a  checkpoint
113                     if  no metadata update is going.  This mode is equivalent
114                     to the ordered data mode of the  ext3  filesystem  except
115                     for  the updates on data blocks still conserve atomicity.
116                     This will improve synchronous write performance for over‐
117                     writing.  This is the default mode.
118
119              strict Apply  strict  in-order semantics that preserves sequence
120                     of all file  operations  including  overwriting  of  data
121                     blocks.   That means, it is guaranteed that no overtaking
122                     of events occurs in the recovered  file  system  after  a
123                     crash.   Unlike  journaling  filesystems, NILFS2 does not
124                     write a same block twice to disk.  So there is no signif‐
125                     icant  performance  degradation  in  comparison  with the
126                     relaxed mode except for file overwriting.
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128       norecovery
129              Disable recovery of the  filesystem  on  mount.   This  disables
130              every  write  access on the device for read-only mounts or snap‐
131              shots.  This option will fail for r/w mounts on an unclean  vol‐
132              ume.
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134       discard / nodiscard
135              These  options  enable/disable  (default is disabled) the use of
136              discard/TRIM commands.  The discard/TRIM commands  are  sent  to
137              the underlying block device when blocks are freed.  This is use‐
138              ful for SSD devices and sparse/thinly-provisioned  LUNs.  (since
139              2.6.34).
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RETURN CODES

142       The return codes of mount.nilfs2 conform to those of mount(8); the fol‐
143       lowing codes could be returned (the bits can be ORed):
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145       0      success
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147       1      incorrect invocation or permissions
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149       2      system error (out of memory, cannot fork, no more loop devices)
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151       4      internal bug
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153       8      user interrupt
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155       16     problems writing or locking /etc/mtab
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157       32     mount failure
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159       64     some mount succeeded
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AUTHOR

162       mount.nilfs2 is written by Ryusuke Konishi  <konishi.ryusuke@gmail.com>
163       for NILFS2, based on the mount program included in the util-linux pack‐
164       age.
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AVAILABILITY

167       mount.nilfs2 is part of the nilfs-utils package and is  available  from
168       https://nilfs.sourceforge.io.
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SEE ALSO

171       nilfs(8), mount(8), umount.nilfs2(8), nilfs_cleanerd(8), lscp(1).
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175nilfs-utils version 2.2            Apr 2014                    MOUNT.NILFS2(8)
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