for HP servers using native LVM the steps are pretty simple, your HPUX admins should know this.
1) pvcreate new disks from VMAX
2) vgextend new disks into the volume group
3) begin mirroring each logical volume (lvextend -m 1 lvname)
4) after mirroring has finished, remove mirror from the old disk (lvreduce -m 0 lvname /dev/dsk/olddiskname)
5) remove old disk from volume group (vgreduce vgname /dev/dsk/olddiskname)
Thanks for the response Dynamox, is it same for Solaris too, I appreciate, if you or someone could shed some light RoboCopy for windows.
what volume manager is running on Solaris ?
For windows hosts running PowerPath look into using PowerPath migrator enabler ..it's free , it's online and it's easy.
on step 3 (lvextend), its is better to specify the physical device(s)name too so the mirror extents will be picked from them only. Other wise , if the existing/old disk has free space there is a possibility the mirror extents may get picked from there. we even create a dummy LV to keep the exisitng disks fully occupied then mirror it w/o specifying any PV argument.