Which RAID setup is not recommended for Amazon EBS?

You are setting up some EBS volumes for a customer who has requested a setup which includes a RAID (redundant array of inexpensive disks). AWS has some recommendations for RAID setups.

Which RAID setup is not recommended for Amazon EBS?
A . RAID 5 only
B . RAID 5 and RAID 6
C . RAID 1 only
D . RAID 1 and RAID 6

Answer: B

Explanation:

With Amazon EBS, you can use any of the standard RAID configurations that you can use with a traditional bare metal server, as long as that particular RAID configuration is supported by the operating system for your instance. This is because all RAID is accomplished at the software level. For greater I/O performance than you can achieve with a single volume, RAID 0 can stripe multiple volumes together; for on-instance redundancy, RAID 1 can mirror two volumes together.

RAID 5 and RAID 6 are not recommended for Amazon EBS because the parity write operations of these RAID modes consume some of the IOPS available to your volumes.

Reference: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/raid-config.html