> my point was that, once i have my box set up pretty much > the way i want, i can mount /usr RO Try making /etc readonly also, but /etc/mtab will make troubles. > 1) i can't accidentally damage anything, even as root If you don't trust root, make regular CD-R backups. > 2) there's not much need for journalling at this point Journalling filesystems don't write journal while reading data. > after all, at this point, i could even support /usr off of > a CD with an ISO9660 filesystem (no, i have no intention of > doing that, but it's theoretically possible.) is there a > linux-supported read-only filesystem that is designed for > pure speed? It would be hard to update system, need to rebuild RO image of /usr from RW original after each change. Run readonly benchmarks of filesystems (for example ext2, ext3, reiserfs, ufs, jfs, udf) and select one with best readonly performance.
