.I errors-behavior
]
[
+.B \-f
+]
+[
.B \-i
.I interval-between-checks
]
.I reserved-blocks-percentage
]
[
+.B \-o
+.RI [^] mount-options [,...]
+]
+
+[
.B \-r
.I reserved-blocks-count
]
.RI [^] feature [,...]
]
[
+.B \-T
+.I time-last-checked
+]
+[
.B \-U
.I UUID
]
Adjust the maximal mounts count between two filesystem checks. If
.I max-mount-counts
is 0 then the number of times the filesystem is mounted will be disregarded
-by e2fsck and the kernel.
+by
+.BR e2fsck (8)
+and the kernel.
+.sp
+Staggering the mount-counts at which filesystems are forcibly
+checked will avoid all filesystems being checked at one time
+when using journaled filesystems.
+.sp
+You should strongly consider the consequences of disabling
+mount-count-dependent checking entirely. Bad disk drives, cables,
+memory, and kernel bugs could all corrupt a filesystem without
+marking the filesystem dirty or in error. If you are using
+journaling on your filesystem, your filesystem will
+.B never
+be marked dirty, so it will not normally be checked. A
+filesystem error detected by the kernel will still force
+an fsck on the next reboot, but it may already be too late
+to prevent data loss at that point.
+.sp
+See also the
+.B \-i
+option for time-dependent checking.
.TP
.BI \-C " mount-count"
Set the number of times the filesystem has been mounted.
.TP
.BI \-e " error-behavior"
Change the behavior of the kernel code when errors are detected.
+In all cases, a filesystem error will cause
+.BR e2fsck (8)
+to check the filesystem on the next boot.
.I error-behavior
can be one of the following:
.RS 1.2i
Cause a kernel panic.
.RE
.TP
+.B \-f
+Force the tune2fs operation to complete even in the face of errors. This
+option is useful when removing the
+.B has_journal
+filesystem feature from a filesystem which has
+an external journal (or is corrupted
+such that it appears to have an external journal), but that
+external journal is not available.
+.sp
+.B WARNING:
+Removing an external journal from a filesystem which was not cleanly unmounted
+without first replaying the external journal can result in
+severe data loss and filesystem corruption.
+.TP
.BI \-g " group"
Set the group which can use reserved filesystem blocks.
The
.B m
in months, and
.B w
-in weeks. A value of zero will disable the timedependent checking.
+in weeks. A value of zero will disable the time-dependent checking.
+.sp
+It is strongly recommended that either
+.B \-c
+(mount-count-dependent) or
+.B \-i
+(time-dependent) checking be enabled to force periodic full
+.BR e2fsck (8)
+checking of the filesystem. Failure to do so may lead to filesystem
+corruption due to bad disks, cables, memory, or kernel bugs to go
+unnoticed until they cause data loss or corruption.
.TP
-.B -j
+.B \-j
Add an ext3 journal to the filesystem. If the
.B \-J
-option is not specified, the default journal parameters will used will create
+option is not specified, the default journal parameters will be used to create
an appropriately sized journal (given the size of the filesystem)
stored within the filesystem. Note that you must be using a kernel
which has ext3 support in order to actually make use of the journal.
.TP
-.BR \-J " journal_options"
+.BR \-J " journal-options"
Override the default ext3 journal parameters. Journal options are comma
separated, and may take an argument using the equals ('=') sign.
The following journal options are supported:
.TP
.BI size= journal-size
Create a journal stored in the filesystem of size
-.IR journal-size .
-The size of the journal must be between 1024 and 10,240 filesystem blocks and
-there must be sufficient free space in the filesystem to create a journal of
+.I journal-size
+megabytes. The size of the journal must be at least 1024 filesystem blocks
+(i.e., 1MB if using 1k blocks, 4MB if using 4k blocks, etc.)
+and may be no more than 102,400 filesystem blocks.
+There must be enough free space in the filesystem to create a journal of
that size.
@JDEV@.TP
@JDEV@.BI device= external-journal
-@JDEV@Add an external journal found on a block device
-@JDEV@named by
-@JDEV@.I external-journal
-@JDEV@to the filesystem.
+@JDEV@Attach the filesystem to the journal block device located on
+@JDEV@.IR external-journal .
@JDEV@The external
@JDEV@journal must have been already created using the command
+@JDEV@.IP
@JDEV@.B mke2fs -O journal_dev
-@JDEV@.IR journal-device.
+@JDEV@.I external-journal
+@JDEV@.IP
+@JDEV@Note that
+@JDEV@.I external-journal
+@JDEV@must be formatted with the same block
+@JDEV@size as filesystems which will be using it.
+@JDEV@.IP
+@JDEV@Instead of specifying a device name directly,
+@JDEV@.I external-journal
+@JDEV@can also be specified by either
+@JDEV@.BI LABEL= label
+@JDEV@or
+@JDEV@.BI UUID= UUID
+@JDEV@to locate the external journal by either the volume label or UUID
+@JDEV@stored in the ext2 superblock at the start of the journal. Use
+@JDEV@.BR dumpe2fs (8)
+@JDEV@to display a journal device's volume label and UUID. See also the
+@JDEV@.B -L
+@JDEV@option of
+@JDEV@.BR tune2fs (8).
.RE
@JDEV@.IP
@JDEV@Only one of the
.I volume-label
is longer than 16 characters,
.B tune2fs
-will truncate it and print a warning.
+will truncate it and print a warning. The volume label can be used
+by
+.BR mount (8),
+.BR fsck (8),
+and
+.BR /etc/fstab (5)
+(and possibly others) by specifying
+.BI LABEL= volume_label
+instead of a block special device name like
+.BR /dev/hda5 .
.TP
.BI \-m " reserved-blocks-percentage"
Set the percentage of reserved filesystem blocks.
.BI \-M " last-mounted-directory"
Set the last-mounted directory for the filesystem.
.TP
-.BI \-O " \fR[^]\fIfeature\fR[,...]"
-set or clear the indicated filesystem features (options) in the filesystem.
+.BR \-o " [^]\fImount-option\fR[,...]"
+Set or clear the indicated default mount options in the filesystem.
+Default mount options can be overriden by mount options specified
+either in
+.BR /etc/fstab (5)
+or on the command line arguments to
+.BR mount (8).
+Older kernels may not support this feature; in particular,
+kernels which predate 2.4.20 will almost certainly ignore the
+default mount options field in the superblock.
+.IP
+More than one mount option can be cleared or set by separating
+features with commas. Mount options prefixed with a
+caret character ('^') will be cleared in the filesystem's superblock;
+mount options without a prefix character or prefixed with a plus
+character ('+') will be added to the filesystem.
+.IP
+The following mount options can be set or cleared using
+.BR tune2fs :
+.RS 1.2i
+.TP
+.B debug
+Enable debugging code for this filesystem.
+.TP
+.B bsdgroups
+Emulate BSD behaviour when creating new files: they will take the group-id
+of the directory in which they were created. The standard System V behaviour
+is the default, where newly created files take on the fsgid of the current
+process, unless the directry has the setgid bit set, in which case it takes
+the gid from the parent directory, and also gets the setgid bit set if it is
+directory itself.
+.TP
+.B user_xattr
+Enable user-specified extended attributes.
+.TP
+.B acl
+Enable Posix Access Control Lists.
+.TP
+.B uid16
+Disables 32-bit UIDs and GIDs. This is for interoperability with
+older kernels which only store and expect 16-bit values.
+.TP
+.B journal_data
+When the filesystem is mounted with journalling enabled, all data
+(not just metadata) is committed into the journal prior to being written
+into the main filesystem.
+.TP
+.B journal_data_ordered
+When the filesystem is mounted with journalling enabled, all data is forced
+directly out to the main file system prior to its metadata being commutted
+to the journal.
+.TP
+.B journal_data_writeback
+When the filesystem is mounted with journalling enabled, data may be
+written into the main filesystem after its metadata has been commutted
+to the journal. This may increase throughput, however, it may allow old
+data to appear in files after a crash and journal recovery.
+.RE
+.TP
+.BR \-O " [^]\fIfeature\fR[,...]"
+Set or clear the indicated filesystem features (options) in the filesystem.
More than one filesystem feature can be cleared or set by separating
features with commas. Filesystem features prefixed with a
caret character ('^') will be cleared in the filesystem's superblock;
character ('+') will be added to the filesystem.
.IP
The following filesystem features can be set or cleared using
-.BR
-tune2fs :
+.BR tune2fs :
.RS 1.2i
.TP
-.B sparse_super
-Limit the number of backup superblocks to save space on large filesystems.
+.B dir_index
+Use hashed b-trees to speed up lookups in large directories.
.TP
.B filetype
-Store file type information in
-directory entries.
+Store file type information in directory entries.
.TP
.B has_journal
-Create an ext3 journal (as if using the
+Use a journal to ensure filesystem consistency even across unclean shutdowns.
+Setting the filesystem feature is equivalent to using the
.B \-j
-option).
+option.
+.TP
+.B sparse_super
+Limit the number of backup superblocks to save space on large filesystems.
.RE
.IP
-After setting or clearing any filesystem feature,
+After setting or clearing
+.B sparse_super
+and
+.B filetype
+filesystem features,
+.BR e2fsck (8)
+must be run on the filesystem to return the filesystem to a consistent state.
+.B Tune2fs
+will print a message requesting that the system administrator run
.BR e2fsck (8)
-must be run on the filesystem to return the filesystem to a
-consistent state.
-This option must not be used on mounted filesystems.
+if necessary.
.IP
.B Warning:
-Linux kernels before 2.0.39 do not support the sparse_super
-or filetype features; neither do all Linux 2.1 kernels.
-Enabling certain filesystem features
-may prevent the filesystem from being mounted on older kernels.
+Linux kernels before 2.0.39 and many 2.1 series kernels do not support
+the filesystems that use any of these features.
+Enabling certain filesystem features may prevent the filesystem from
+being mounted by kernels which do not support those features.
.TP
.BI \-r " reserved-blocks-count"
Set the number of reserved filesystem blocks.
.TP
-.BI \-s " sparse_super_flag"
-set or reset the sparse_superblock flag. The sparse_super feature
+.BR \-s " [" 0 | 1 ]
+Turn the sparse super feature off or on. Turning this feature on
saves space on really big filesystems. This is the same as using the
.B "\-O sparse_super"
option.
.IP
.B Warning:
-The Linux kernels before 2.0.39 do not support this feature. Neither do
+Linux kernels before 2.0.39 do not support this feature. Neither do
all Linux 2.1 kernels; please don't use this unless you know what you're
doing! You need to run
.BR e2fsck (8)
on the filesystem after changing this feature in order to have a valid
filesystem.
.TP
+.BI \-T " time-last-checked"
+Set the time the filesystem was last checked using
+.BR e2fsck .
+This can be useful in scripts which use a Logical Volume Manager to make
+a consistent snapshot of a filesystem, and then check the filesystem
+during off hours to make sure it hasn't been corrupted due to
+hardware problems, etc. If the filesystem was clean, then this option can
+be used to set the last checked time on the original filesystem. The format
+of
+.I time-last-checked
+is the international date format, with an optional time specifier, i.e.
+YYYYMMDD[[HHMM]SS]. The keyword
+.B now
+is also accepted, in which case the last checked time will be set to the
+current time.
+.TP
.BI \-u " user"
Set the user who can use the reserved filesystem blocks.
.I user
is converted to a numerical uid before it is stored in the superblock.
.TP
.BI \-U " UUID"
-set the universally unique identifier (UUID) of the filesystem to
+Set the universally unique identifier (UUID) of the filesystem to
.IR UUID .
-The format of the UUID is a series of hex digits separated by hypthens,
+The format of the UUID is a series of hex digits separated by hyphens,
like this:
"c1b9d5a2-f162-11cf-9ece-0020afc76f16".
The
generate a new time-based UUID
.RE
.IP
+The UUID may be used by
+.BR mount (8),
+.BR fsck (8),
+and
+.BR /etc/fstab (5)
+(and possibly others) by specifying
+.BI UUID= uuid
+instead of a block special device name like
+.BR /dev/hda1 .
+.IP
See
.BR uuidgen (8)
for more information.
.B tune2fs
uses the ext2fs library written by Theodore Ts'o <tytso@mit.edu>.
This manual page was written by Christian Kuhtz <chk@data-hh.Hanse.DE>.
-Timedependent checking was added by Uwe Ohse <uwe@tirka.gun.de>.
+Time-dependent checking was added by Uwe Ohse <uwe@tirka.gun.de>.
.SH AVAILABILITY
.B tune2fs
-is part of the e2fsprogs package and is available from anonymous
+is part of the e2fsprogs package and is available from
http://e2fsprogs.sourceforge.net.
.SH SEE ALSO
.BR dumpe2fs (8),
git://git.whamcloud.com / tools / e2fsprogs.git / blobdiff