I'm trying to create a raid 6 array on a VNX 5100 from EMC, however am unable to create one with 7 drives. We have 8 total, and I immediately carved one out for hot sparing, leaving me 7 data drives. I can create one with 6 or 8, not 7. I am also unable to make a raid with 5 drives, which leads me to believe that odd numbers of disks are not eligible for raid 6. Raid 5 gives me no such issues.
Raid 6 should not have a dependency on having an even number of drives. Its only dependency should be meeting the minimum number of 4 drives. Can anyone help me find a way around this?
EMC implements RAID6 using the EVENODD technique, which requires an even number of disks.
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.88.332
Here's an EMC PDF. Page 6 is what you are looking for.