SAN attack: AWS speeds up slow SSD block volume instances

Less than a year after introducing its first SSD-based performance block storage, AWS has finally caught up with modern SSD and SAN speed with its latest io2 Block Express volume — quadrupling performance, capacity and throughput, but at the same price.

AWS’s announcement declares the volume is the next-generation storage server architecture that provides the highest block storage performance without the cost or hassle of having to procure, scale, and maintain expensive on-premises SANs. 

Mai-Lan Tomsen Bukovec.

Mai-Lan Tomsen Bukovec, VP Storage, at AWS, provided the announcement quote: “io2 Block Express volumes are a game changer. Customers can scale their capacity by petabytes in minutes at as low as half the cost of a typical SAN, and the storage is managed by AWS with the same or better performance of many leading SAN storage products, and without the hassle of procuring, scaling, and maintaining an on-premises SAN.”

AWS claims io2 Block Express volumes reinvent block storage, giving customers SAN-level performance with the elasticity of AWS, unlimited scale, and the flexibility of pay-as-you-go pricing; at as low as half the cost of a typical SAN (see bootnote below). 

AWS’s Elastic Block Storage (EBS) comes in three basic types: SSD, HDD and Previous Generation. The SSD type is divided into two sub-types: General Purpose SSD and Provisioned IOPS SSD, with the latter volumes typically being larger in capacity and faster in performance.

There were two kinds of provisioned IOPS SSD volumes: 

  • io1 — with 99.8 to 99.9 per cent durability and a 0.2 per cent annual failure rate (AFR);
  • Io2 — with 99.99 per cent durability and a 0.0001 per cent AFR.

The io2 storage volume was announced in August 2020 and now the Block Express variant has arrived. A table shows how these three provisioned IOPS volumes compare: 

(A TiB is 1.09951 TB.)

Capacity, IOPS and volume throughput have each increased by 4x compared to basic io2 volumes.

But AWS is behind the technology curve here — all-flash SAN arrays were promoting their sub-millisecond access before 2015. For example, Pure’s FlashArray FA-400 announced in May 2014, offered less than one millisecond average latency. It has taken AWS years to catch up.

Amazon says io2 Block Express volumes are designed for applications that benefit from high-volume IOPS, high throughput, high durability, high storage capacity, and low latency. For example, using its Elastic Compute Cloud (EC2) R5b instances and io2 Block Express volumes, SQL Server runs up to 3x faster on AWS than the next fastest cloud provider — meaning, we expect, Azure.

Multiple io2 Block Express volumes can be striped together to get better performance, as can multiple io2 volumes.

It says that its Block Express scheme helps io2 volumes achieve this performance by completely reinventing the underlying EBS hardware, software, and networking stacks. Specifically the network stack uses a high-performance Scalable Reliable Datagrams (SRD) protocol to reduce latency. There is an AWS tech talk about SRD here.

AWS says io2 Block Express volumes are available at the same price as io2 volumes, with no upfront commitments to use the volumes. There is AWS information about these fast new io2 volumes here.

Bootnote: This point may strike readers of the Andreessen Horowitz Trillion Dollar Paradox article by Sarah Wang and Martin Lomax as somewhat hard to believe over the long haul. The article details how “Dropbox detailed in its S-1 a whopping $75M in cumulative savings over the two years prior to IPO due to their infrastructure optimisation overhaul, the majority of which entailed repatriating workloads from public cloud.”