The AWS Storage Gateway is a software-based appliance that connects to the network via iSCSI and asynchronously uploads point-in-time snapshots to the Amazon's Simple Storage Service (S3). It can also be used to mirror data on Windows or Linux file or application servers to Amazon's EC2 for disaster recovery. Snapshots can be scheduled at 1-, 2-, 4-, 8-, 12-, or 24-hour intervals or created in an ad hoc fashion. They include only data that has changed since the last snapshot.
The gateway stores data on Amazon S3 as an Amazon Elastic Block Store (EBS) snapshot and data is encrypted at Amazon S3 using AES-256 encryption. Data is transported to Amazon in a compressed format and encrypted via the Secure Sockets Layer (SSL) protocol. Each AWS Storage Gateway can support as much as 12TB of on-premises storage and as many as 12 volumes.
Volumes can at present be stored on the gateway for fast recovery. In the future, Amazon will make available gateway-cached volumes, which will use the local storage as a cache for frequently accessed data, while the actual copy of the data will live in the cloud.
[ Read about Amazon's cloud service for databases. See Amazon DynamoDB: Big Data's Big Cloud Moment. ]
At Amazon S3, data is protected by redundantly storing it on multiple devices across multiple facilities in a region. The gateway is installed on a server running VMware ESXi Hypervisor with four virtual processors and 7.5GB of RAM assigned to the virtual machine that hosts it. It also requires 75GB of disk space for the virtual machine files and system data.
The introduction of the AWS Storage Gateway gives validation to cloud storage vendors such as Nirvanix, Nasuni, and TwinStrata, all of whom had gateways of their own.
Unlike other cloud storage gateways, the AWS Storage Gateway works only with VMware and not Microsoft's Hyper-V or Citrix XenServer. Further, the AWS Storage Gateway locks customers into working with Amazon exclusively. Users of both TwinStrata's CloudArray and Nasuni's Filer have a choice of cloud storage providers and can easily transfer their data from one cloud storage provider to another.
The AWS Storage Gateway beta version is not inexpensive--while Amazon offers 60 days of free use, once activated, the gateway costs $125 per month. Users also get 1GB of storage for Amazon EBS snapshots and 15GB of data transferred out of AWS. Snapshot storage pricing starts at $0.14 per gigabyte per month.
Deni Connor is founding analyst for Storage Strategies NOW, an industry analyst firm that focuses on storage, virtualization, and servers.
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