Upgrading 2 mirrored 36gb to 2 72 gb hdd

I have a two 36bg scsi hdd that are configured with raid 1(mirrored) on ml 350 g3. now im running out of space and i want to upgrade it with two 72gb hdd, how can i possibly copy the exact data on the first mirrored hdd to a new two 72gb hdd without losing any single files?
tnx in advance