Disk space is cheap, but fscking a large volume takes forever. It would be good if online/background fsck was available, like it is for ufs/freebsd.
We have some ideas around improving fsck performance with a combination of readahead and lazy initialisation of on-disk data structures. But background fsck is not on the roadmap and is not currently under consideration by the ext3 maintainers; and given the complexity of an implementation, this is unlikely to change in the short term.
Thanks for the helpful reply. Would you also consider a more intelligent (non-restarting) fsck too? (bug 178468)