Some background info, with RAID 5 on DMX-3/4 (pre-VMAX)  the M1 position is used for marking data tracks valid/invalid, and the M2 is for the parity tracks.  Of course, both data and parity tracks are striped across all members of the group, so it's not quite the same as RAID 1 which has one mirror position for each drive in the group (again, talking pre-VMAX).  *I'm an Inlines guy, hope this answers more questions than it creates [IMAGE]  Mike
2-way mirror device occupies 2 mirror position, 3-way mirror occupies 3 mirror positions, 4 -way mirror occupies 4 mirror positions but cant comprehend raid-5 occupying m1 and m2 positons since its in effect pointing to the same disks without any extra copy in the actual volume.....   Thanks in advance
raid 5 device