Converting Ext2fs to Ext3fs

One of the advantages of ext3fs over the other journaling filesystems is that it's easy to turn an existing ext2 filesystem into an ext3 filesystem. You can do this using the tune2fs program and its-j option:

If the filesystem to which you add a journal is mounted when you make this change, tune2fs creates the journal as a regular file, called .journal, in the filesystem's root directory. If the filesystem is unmounted when you run this command, the journal file doesn't appear as a regular file. In either case, the filesystem is now an ext3 filesystem, and it can be used just as if you created it as an ext3 filesystem initially. If necessary, you may be able to access the filesystem as ext2fs (say, using a kernel that has no ext3fs support); however, some older kernels and non-Linux utilities may refuse to access it in this way, or they may provide merely read-only access.

On rare occasion, an ext3 filesystem's journal may become so corrupted that it interferes with disk recovery operations. In such cases, you can convert the filesystem back into an ext2 filesystem using the debugfs tool:

debugfs 1.32 (09-Nov-2002)

debugfs: features -needs_recovery -hasjournal

Filesystem features: dirjndex filetype sparse_super debugfs: quit

After performing this operation, you should be able to use fsck.ext2 with its -f option, as described in the upcoming section, "Filesystem Check Options," to recover the filesystem. The newly-deactivated journal will cause fsck.ext2 to report errors even if the filesystem did not previously have them. If you like, you can then add the journal back by using tune2fs, as just described.

Warning Don't try to remove the journal from a mounted filesystem.

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