“Magnetic disks are rapidly starting to exhibit tape-like properties and with modern workloads being increasingly random, they are becoming less and less suitable as a storage system.”
Werner Vogels, All Things Distributed, 7/19/12
Yesterday morning Amazon announced high I/O EC2 instances designed to run low-latency I/O intensive applications. Building on their initial foray into SSD-based storage, this new service allows a customer to provision dedicated SSD from local storage for each instance. Designed only for EC2 instances the use case is limited to ephemeral storage (i.e. no EBS equivalent). From a cost perspective Amazon is charging $3.10 per instance hour compared to $1.30 for the closest disk-based equivalent. Based on a 30-day month this rolls up to $2200 per month or $0.65/GB/month. In its current form the service is delivered in only one package (2TB of local storage, visible as 2 x 1TB volumes), lacking the ability to tailor storage performance or capacity to workloads that don’t fit this profile.
Most SSD-based cloud offerings today have taken a very similar approach to what Amazon has announced today…local SSD’s in a box. All the typical tradeoffs of local versus shared storage still apply; lack of sharing or multi-tenancy, no high availability, inability to move data between instances. For some workloads like Mongo or Cassandra this solution should suffice. For traditional enterprise applications however, the lack of reliability remains a major sticking point. Moreover, to achieve the price points required to attract a broader range of applications will require a multi-tenant infrastructure.
Harping further on the limitations of the initial offering misses the broader implications of this announcement. The performance inconsistency that exists in most cloud environments is the most frequently cited barrier to broader adoption of more I/O intensive applications in the cloud. Amazon’s broader adoption of SSDs in their cloud portfolio is an extremely important milestone for cloud computing and strong directional indicator of where the market is going. In short order, we fully expect more cloud providers to follow in their footsteps. The good news for now is that Amazon has left the door open for others to come along with a differentiated value proposition. However, when it comes to SSDs in the cloud the train is clearly leaving the station…all aboard!!!