System information
For striped block devices (for example, RAID5 arrays), the stripe geometry can be specified at the time
of file system creation. Using proper stripe geometry greatly enhances the performance of an ext4 file
system.
When creating file systems on LVM or MD volumes, mkfs. ext4 chooses an optimal geometry. This
may also be true on some hardware RAIDs which export geometry information to the operating
system.
To specify stripe geometry, use the -E option of mkfs. ext4 (that is, extended file system options)
with the following sub-options:
st rid e= value
Specifies the RAID chunk size.
st rip e- wid t h = value
Specifies the number of data disks in a RAID device, or the number of stripe units in the
stripe.
For both sub-options, value must be specified in file system block units. For example, to create a file
system with a 64k stride (that is, 16 x 4096) on a 4k-block file system, use the following command:
# mkfs. ext4 -E stri de= 16 ,stri pe-wi d th= 6 4 /d ev/device
For more information about creating file systems, refer to man mkfs. ext4 .
Important
It is possible to use tune2fs to enable some ext4 features on ext3 file systems, and to use the
ext4 driver to mount an ext3 file system. These actions, however, are not supported in Red Hat
Enterprise Linux 6, as they have not been fully tested. Because of this, Red Hat cannot
guarantee consistent performance and predictable behavior for ext3 file systems converted or
mounted in this way.
6.2. Mount ing an Ext 4 File Syst em
An ext4 file system can be mounted with no extra options. For example:
# mo unt /d ev/device /mount/point
The ext4 file system also supports several mount options to influence behavior. For example, the acl
parameter enables access control lists, while the user_xattr parameter enables user extended
attributes. To enable both options, use their respective parameters with -o , as in:
# mo unt -o acl ,user_xattr /d ev/device /mount/point
The tune2fs utility also allows administrators to set default mount options in the file system
superblock. For more information on this, refer to man tune2fs.
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