-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Tim wrote: > Now I'm wondering if dirhash means adding some sort of checksum to a > filing system. No. It's really not as mysterious as this thread makes it sound. The ext3 and ext4 filesystems have a flag called "dir_index". You can enable it using tune2fs for quite some time. It's a feature that was introduced after ext3 was first released and because of this (and the fact that new features have to be tested first) it is not enabled by default by older releases. Times apparently changed. The "Adding dirhash hint to *" message comes from e2fsck, the file system integrity checker for these types for filesystem. It found the feature is not enabled and now that it is stable enough it makes sense to enable it unconditionally. So it did and warned the user about it. This feature, just as the tune2fs man page says, speeds up searching in large directories. With the traditional mechanism finding a file in a large directory is a linear process: files entries are looked at one by one until the right one is found. With dir_index enabled a hash table is used which allows to find each file in a constant time, potentially significantly speeding up the file lookup. So, nothing devious is going on. It's just that the maintainers of the tools know that most people do not know about the new features and/or will not enable new features on their own for fear. This is why e2fsck does it by itself for safe options. - -- ➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (GNU/Linux) iD8DBQFG0atc2ijCOnn/RHQRAg5VAKC5l9w6oKoOFzjHj/jHnAOpVkXPEACeJnhv SIpsf9xBSdfESUv8ijwigNk= =+zqo -----END PGP SIGNATURE-----
