Hey, Since we are thinking of switching into using the ext4 file systems on some of our machines with purely ext2 partitions, we face the problem of how to migrate all those existing files on ext2 partitions. Seems like there are two major directions to go: 1) do a backup, umount, mke2fs into ext4, and restore In this approach, we may actually take advantage of the layout changes so as to benefit from some features of ext4. 2) umount, tune2fs to add the 'extent' feature, mount back using type ext4, migrate the existing files(directories) one by one through the ioctl EXT4_IOC_MIGRATE Motivated by the ext4 ioctl interface for migration, we are also looking into this in-place approach. But we are mostly concerned with the fact that if the existing files are highly fragmented, will we still get benefit from the extents? Or will we even get hurt by turning the files into being extents-based? Before we do more detailed experiments on both approaches, we are here to ask for advice, suggestion and comments. So If you have ever run into either direction or even both, do you have any experience you can share with us? Or simply express your feeling: Does it work? What could go wrong? Does it take very long to complete the migration(of course, it could depends on the number of files and their data block locations)? Are you happy with the resulting files being migrated? Has anyone every tried approach 2)? How did that work for you? Thanks, Xiang -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
