Hello Sukhbir,
RaidManager is unsupported under Solaris 10. You won't be able to manage the A1000 and the disks. The already configured LUNs are usable without RaidManager.
Maybe you can keep a minimal installation of Solaris 8 or 9 with RaidManager installed. This would allow to manage the A1000, but indeed requires to shutdown and reboot the system to load the other Solaris.
Michael