There is a great formula for RAID5 arrays at this post:
I am looking at creating some RAID6 luns on our Sun Storage Tek 6140 and 6580 sans. We have a range of needs so will be creating semi-large 5 and/or 7 disk RAID arrays up to 14 disk RAID arrays. I believe we will keep the smaller arrays RAID5 but will go RAID6 for the 14 disk stripes. Is there a formula like the one in the post above that will work for RAID6?
Thanks in advance,
RAID 5 and RAID 6 are not different. RAID 6 adds another parity drive, but that's all. The performance will be lower.
You can do the same thing with RAID 5, and get better performance. I wouldn't do RAID 6.
I understand the concept being the same. I am planning on two vertical stripes across 7 trays. In case I lose one tray (two disks) RAID5 would be dead in the water. RAID6 at least has a chance to rebuild (albeit slowly). Speed is not my #1 concern on the 14 disk arrays. Size and uptime are my two priorities. So, if I still want to go RAID6, would I really go with the same formula but just add 2 instead of 1 disk?