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.TH TUNE2FS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
.SH NAME
-tune2fs \- adjust tunable filesystem parameters on ext2/ext3 filesystems
+tune2fs \- adjust tunable filesystem parameters on ext2/ext3/ext4 filesystems
.SH SYNOPSIS
.B tune2fs
[
.SH DESCRIPTION
.BI tune2fs
allows the system administrator to adjust various tunable filesystem
-parameters on Linux ext2/ext3 filesystems.
+parameters on Linux ext2, ext3, or ext4 filesystems. The current values
+of these options can be displayed by using the
+.B -l
+option to
+.BR tune2fs (8)
+program, or by using the
+.BR dumpe2fs (8)
+program.
.SH OPTIONS
.TP
.BI \-c " max-mount-counts"
before moving to next disk. This mostly affects placement of filesystem
metadata like bitmaps at
.BR mke2fs (2)
-time to avoid placing them on a single disk, which can hurt the performanace.
+time to avoid placing them on a single disk, which can hurt the performance.
It may also be used by block allocator.
.TP
-.BI stripe-width= stripe-width
+.BI stripe_width= stripe-width
Configure the filesystem for a RAID array with
.I stripe-width
filesystem blocks per stripe. This is typically be stride-size * N, where
This allows the block allocator to prevent read-modify-write of the
parity in a RAID stripe if possible when the data is written.
.TP
+.BI hash_alg= hash-alg
+Set the default hash algorithm used for filesystems with hashed b-tree
+directories. Valid algorithms accepted are:
+.IR legacy ,
+.IR half_md4 ,
+and
+.IR tea .
+.TP
.B test_fs
Set a flag in the filesystem superblock indicating that it may be
mounted using experimental kernel code, such as the ext4dev filesystem.
@JDEV@options can be given for a filesystem.
.TP
.B \-l
-List the contents of the filesystem superblock.
+List the contents of the filesystem superblock, including the current
+values of the parameters that can be set via this program.
.TP
.BI \-L " volume-label"
Set the volume label of the filesystem.
.BR tune2fs :
.RS 1.2i
.TP
+.B large_file
+Filesystem can contain files that are greater than 2GB. (Modern kernels
+set this feature automatically when a file > 2GB is created.)
+.TP
.B dir_index
Use hashed b-trees to speed up lookups in large directories.
.TP
future.
.B Tune2fs
only supports clearing this filesystem feature.
+.TP
+.B uninit_bg
+Allow the kernel to initialize bitmaps and inode tables and keep a high
+watermark for the unused inodes in a filesystem, to reduce
+.BR e2fsck (8)
+time. This first e2fsck run after enabling this feature will take the
+full time, but subsequent e2fsck runs will take only a fraction of the
+original time, depending on how full the file system is.
.RE
.IP
After setting or clearing
.BR sparse_super ,
+.BR uninit_bg ,
.BR filetype ,
or
.B resize_inode
feature,
.B e2fsck -D
can be run to convert existing directories to the hashed B-tree format.
+Enabling certain filesystem features may prevent the filesystem from being
+mounted by kernels which do not support those features. In particular the
+.BR uninit_bg
+and
+.BR flex_bg
+features are only supported by the ext4 filesystem.
.TP
.BI \-r " reserved-blocks-count"
Set the number of reserved filesystem blocks.
.TP
-.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.
-.TP
.BI \-T " time-last-checked"
Set the time the filesystem was last checked using
.BR e2fsck .
+The time is interpreted using the current (local) timezone.
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
is part of the e2fsprogs package and is available from
http://e2fsprogs.sourceforge.net.
.SH SEE ALSO
+.BR debugfs (8),
.BR dumpe2fs (8),
.BR e2fsck (8),
.BR mke2fs (8)
git://git.whamcloud.com / tools / e2fsprogs.git / blobdiff