Redo configuration again with output from metastat -p. Important files to go through are /etc/lvm/md.tab, /etc/lvm/mddb.cf, /etc/lvm/md.cf files. Dont forget to insert echo "set md:mirrored_root_flag = 1" >> /etc/system file for solaris 9. Also delete metadb's forcefully as well before rebooting then reconfigure again.The iostat count will become zero once you restarted.
You can try by reconfiguring SVM. If its still generating hard errors then no choice need to replace the hard disk.