It is recommended that those wishing to make use of ext4 start with a freshly formatted partition. However, you may install Red Hat Enterprise Linux 6 with the ext4migrate boot option if you wish to convert your legacy ext3 partitions to ext4. It is important to note that by doing this you will not receive all of the benefits ext4 offers, since the data currently residing on the partition will not make use of the extents features and other changes. New data will however make use of extents. Passing this boot option to migrate to ext4 is not recommended and it is strongly recommended that you back up file systems before attempting this migration.
Red Hat Enterprise Linux 6 provides full support for ext4 and it is the default file system for new installations. This section explains the major changes in behaviour that this new file system introduces.
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The included version of the GRUB bootloader provides full support for ext4 partitions. The installer also allows you to place any /boot file system on an ext4 partition.
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The included version of the e2fsprogs package is fully compatible with ext4.
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In some cases, ext4 file systems created under Red Hat Enterprise Linux 5.3 with the e4fsprogs package created an ext4dev file system type. The test_fs feature flag identifying these file systems as a development version can be removed with the following command: tune2fs -E ^test_fs. This is done so that these file systems will be recognized as regular ext4 file systems.
