Why can't I use the new stl / sc1 EBS AWS volumes as root volumes

Question

AWS recently launched the sc1 and st1 HDD types of hard drives, I cannot use them as root volumes when starting new EC2 instances or starting from an already created AMI (both of them).

I chose the m4 machine, in any case, the root volume is EBS itself, below is a screenshot, the second volume that I add receives new parameters, but I can not select the first one. Is it designed by AWS people?

Answer 1

If you look at http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSVolumeTypes.html

under the main table for a volume type like Throughput Optimized HDD (st1) and Cold HDD (sc1) it says

Cannot be boot volume

and below

Performance Optimized hard drive sizes (st1) provide a low-cost magnetic drive that determines performance in terms of throughput, not IOPS. This volume type is suitable for large sequential workloads such as Amazon EMR, ETL, data warehousing, and log processing. Boot st1 strings are not supported.

and

The cold hard drive volumes (sc1) provide low-cost magnetic storage that determines performance in terms of bandwidth rather than IOPS. With a lower bandwidth limit than st1, sc1 is ideal for large, consistent cold data workloads. If you need infrequent access to your data and want to save money, sc1 provides an inexpensive storage unit. Sc1 boot volumes are not supported.

Answer 2

Because customer experience will be terrible. Boot volumes use a little random I / O; these volumes are not intended for small I / O operations. Just use GP2 for boot volumes.