1MOUNT.NILFS2(8) System Manager's Manual MOUNT.NILFS2(8)
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6 mount.nilfs2 - mount a NILFS2 file system
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9 mount -t nilfs2 [-finrvw] [-o options [,...]] device dir
10 mount -t nilfs2 [-finrvw] [-o options [,...]] device | dir
12 mount.nilfs2 [-fnrvw] [-o options [,...]] device dir
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16 mount.nilfs2 serves to attach a NILFS2 file system on the specified
17 directory dir. It is intended to be executed from mount(8), and will
18 invoke the garbage collector nilfs_cleanerd(8) after an actual mount
19 system call has succeeded. Conversely, umount.nilfs2(8) will shutdown
20 the garbage collector before detaching the file system.
21 The standard command line interface is the first form:
23 mount -t nilfs2 [options] device dir
24 This tells the kernel to attach the NILFS2 file system on device at the
25 directory dir. With the second form, the mount program tries to find
26 out a missing device or dir argument from the /etc/fstab table.
27 The third form, which directly invokes mount.nilfs2, is also usable
29 since mount.nilfs2 maintains by itself the system mount state such as
30 the list of mounted file systems described in /etc/mtab. Howerver, the
31 first or the second form is usually recommended because some expansive
32 options are not supported by the third form.
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35 The full set of options used by an invocation of mount(8) is determined
36 by extracting the options from the fstab table, then applying any
37 options specified by the -o argument, and finally applying a -r or -w
38 option, when present.
39 See mount(8) for the full set of options. Commonly used options are as
41 follows:
42 -f Fakes mounting the file system, meaning that the actual system
44 call will be skipped. This option is used to add entries for
45 devices that were mounted earlier with the -n option. It can
46 also be used for invoking nilfs_cleanerd(8) skipped previously.
47 -i Don't call mount.nilfs2. This disables garbage collection and
49 handling of pseudo mount options.
50 -n Mount without writing in /etc/mtab. This is necessary for exam‐
52 ple when /etc is on a read-only file system. With this option,
53 invocation of nilfs_cleanerd(8) is skipped. To add entries to
54 mtab and invoke the garbage collector later, the -f option is
55 available.
56 -r Mount the file system read-only. A synonym is "-o ro".
58 -v Verbose mode.
60 -w Mount the file system read/write. This is the default. A synonym
62 is "-o rw".
63 -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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70 The following options apply only to the NILFS2 filesystem. They all
71 follow the -o flag.
72 nobarrier
74 Disable barrier writes for the block I/O to a lower device. The
75 barrier write serves an important role to ensure consistency of
76 filesystems after a system crash or power failure. NILFS2 uses
77 this feature by default to assure the reliability. For devices
78 not supporting the barrier write, it will be disabled automati‐
79 cally and a warning will be logged.
80 cp=checkpoint-number
82 Specify the checkpoint-number of the snapshot to be mounted.
83 Checkpoints and snapshots are listed by lscp(1). Only the
84 checkpoints marked as snapshot are mountable with this option.
85 Note that the read-only mount option must be specified together.
86 errors=continue / errors=remount-ro / errors=panic
88 Define the behaviour when an error is encountered. (Eigher
89 ignore errors and just mark the file system erroneous and con‐
90 tinue, or remount the file system read-only, or panic and halt
91 the system.) The default is continue.
92 pp=protection-period
94 Specify the protection-period for the cleaner daemon (in sec‐
95 onds). nilfs_cleanerd never deletes recent checkpoints whose
96 elapsed time from its creation is smaller than protection-
97 period.
98 nogc Disable garbage collection. The cleaner daemon will not be
100 started. It can be be started manually, but in that case it
101 must also be stopped manually before unmounting.
102 order=relaxed / order=strict
104 Specify order semantics for file data. Metadata is always writ‐
105 ten to follow the POSIX semantics about the order of filesystem
106 operations.
107 relaxed
109 Apply relaxed order semantics that allows modified data
110 blocks to be written to disk without making a checkpoint
111 if no metadata update is going. This mode is equivalent
112 to the ordered data mode of the ext3 filesystem except
113 for the updates on data blocks still conserve atomicity.
114 This will improve synchronous write performance for over‐
115 writing. This is the default mode.
116 strict Apply strict in-order semantics that preserves sequence
118 of all file operations including overwriting of data
119 blocks. That means, it is guaranteed that no overtaking
120 of events occurs in the recovered file system after a
121 crash. Unlike journaling filesystems, NILFS2 does not
122 write a same block twice to disk. So there is no signif‐
123 icant performance degradation in comparison with the
124 relaxed mode except for file overwriting.
125 norecovery
127 Disable recovery of the filesystem on mount. This disables
128 every write access on the device for read-only mounts or snap‐
129 shots. This option will fail for r/w mounts on an unclean vol‐
130 ume.
131
133 The return codes of mount.nilfs2 conform to those of mount(8); the fol‐
134 lowing codes could be returned (the bits can be ORed):
135 0 success
137 1 incorrect invocation or permissions
139 2 system error (out of memory, cannot fork, no more loop devices)
141 4 internal bug
143 8 user interrupt
145 16 problems writing or locking /etc/mtab
147 32 mount failure
149 64 some mount succeeded
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153 mount.nilfs2 is written by Ryusuke Konishi <ryusuke@osrg.net> for
154 NILFS2, based on the mount program included in the util-linux package.
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157 mount.nilfs2 is part of the nilfs-utils package and is available from
158 http://www.nilfs.org.
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161 nilfs(8), mount(8), umount.nilfs2(8), nilfs_cleanerd(8), lscp(1).
162nilfs-utils version 2.0 May 2008 MOUNT.NILFS2(8)