Hello,  You can't run different RAID levels on the same array member.  Once you set the RAID policy only that policy is possible on that physical member.  You also can't just add a few drives to expand current RAID set.  If you array is 1/2 populated, the upgrade option is only to add another 12 drives of the same size type.  If you use larger drives, only the capacity of the smallest disk will be used.   The drives also must be purchased from Dell, and specifically for the EQL SANs.  Generic drives won't work.  Regards,  Don  
Hello, I have a PS4100 with 12 600GB disks in RAID-50 (4.18TB), and two discs are spare. I want to expand more 1TB and need to know if I can buy more disks and adding the existing Pool. Or I have to buy 3 more disks to a RAID-5? After placing the new disc, the total space of the pool will be available for expansion? Thank you.
Adding new disks in the PS4100