Do Meta/hyper devices created on dmx-3 "share spindles" with other devices

unless your DW application was provisioned from a dedicated disk group, their devices are on "shared" spindles. If you run "symdev show -sid 123 DEVNAME", at the bottom of the output you will see the physical drives where each hyper reside.  For example here is a 8.6G device (not meta), it's raid-5 device (3+1 configuration)

RAID-5 Hyper Devices (3+1):
            {
            Device : 1053
                {
                --------------------------------------------------------------
                 Disk     DA       Hyper       Member    Spare       Disk
                DA :IT   Vol#   Num Cap(MB)  Num Status  Status  Grp#  Cap(MB)
                --------------------------------------------------------------
                02D:Db   3468    37    2878    1 RW      N/A        0   286102
                01C:Db   3444    39    2878    2 RW      N/A        0   286102
                15C:Db   3456    39    2878    3 RW      N/A        0   286102
                16D:Db   3454    37    2878    4 RW      N/A        0   286102
                }
            }
        }

now you could run "symdisk show -sid 123 2D:DB" and see all the symmetrix devices that reside on that physical drive. Repeat for the rest of the drives.