I have a not-so-sophisticated install of FreeBSD on a gmirror of two hard drives. The underlying fs is UFS2 with soft updates. But I can't mount anything useful (specifically: unionfs, nullfs, linproc) on it. I can mount msdosfs. I run many FreeBSD systems, but this is the only one with gmirror, so I ask: is it a gmirror deficiency or did I break something?