Well, if you use /dev/hda2 then it's still only 32MB, and would fsck very fast compared to a 10/20/30 GB partition. It'd still be a very good idea to only make the drive rw for the time needed to write the table, and make it ro again immediately afterwards. But this should only happen on /dev/hda2 or /dev/hdc2...We shouldn't touch any of the existing partitions from an app.

I don't think the issue is so much one of having partitions mounted ro vs. rw as it is that as soon as you start talking about doing this sort of thing, you're destroying all the hard work the empeg guys put into keeping the drives spun down as much as possible.