Bummer

[root@caradhras] # metadb -a -f -c2 c0t0d0s7 c0t1d0s7

Assertion failed: partno vtoc.nparts, file ../common/meta_nameinfo.c, line 628
metadb: Abort
Abort (core dumped)

There seems to be some issues with Disksuite in Solaris 10 Express, which are solved in testbuild s10_70, but not yet incorporate into the latest download version (s10_69). What's worse, is that ZFS isn't included yet (or will never be) in the Solaris 10 Express downloads.