Why can't I use the new st1/sc1 EBS volumes by AWS as root volumes

Question

AWS launched sc1 and st1 HDD EBS volume types recently, I can't seem to use these as root volumes while launching new EC2 instances or launching from already created AMI's (tried both).

I chose an m4 machine, in any case, the root volume is EBS itself, below is a screenshot, the second volume that I add gets the new options, however the first one I can't choose the same. Is this by design AWS people?

Silvan

Answer 1

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

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

Cannot be a boot volume

and below

Throughput Optimized HDD (st1) volumes provide low-cost magnetic storage that defines performance in terms of throughput rather than IOPS. This volume type is a good fit for large, sequential workloads such as Amazon EMR, ETL, data warehouses, and log processing. Bootable st1 volumes are not supported.

and

Cold HDD (sc1) volumes provide low-cost magnetic storage that defines performance in terms of throughput rather than IOPS. With a lower throughput limit than st1, sc1 is a good fit ideal for large, sequential cold-data workloads. If you require infrequent access to your data and are looking to save costs, sc1 provides inexpensive block storage. Bootable sc1 volumes are not supported.

Lanfri

Answer 2

Because the customer experience would be awful. Boot volumes use small, random I/O; these volumes aren't designed for small I/O. Just use GP2 for boot volumes.

Grimaldo

I don't quite understand why it would necessarily be so awful. I have about two dozen VMs on a single local VMware server, a small 10k SAS array, all magnetic, for the boot volumes, and many of them start up in under 30 seconds, and all perform quite adequately... it's probably only got about 840 IOPS, spread across about a dozen VMs running at any given time... – Arabesque