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The uNAS is priced at $0.70 per GB. As our usage increases, we expect to be able to negotiate this price down as we can commit to a specific minimum amount each month. Amazon’s EBS is priced at $0.10GB of provisioned storage. The key here is “provisioned”. With the uNAS you have “unlimited” available disk space and pay for what you actually use. With EBS you have to set up a pre-defined amount e.g. 100GB, and you pay for that regardless of whether you’re using 1GB or 100GB.

You would need to provision more than you are using with EBS because re-provisioning the volume requires taking a snapshot of the data and starting up a new volume from that snapshot. This takes time and involves downtime whilst the volume is built.

EBS also has other charges – $0.10 per 1 million I/O requests. When we tested EBS over a 24 hour period, we used 100 million I/O requests. There are also backup (snapshot) fees because you are backing up to S3. These are priced at $0.15 per GB-month of data stored and there are fees for PUT and GET requests. Whilst the “at a glance” pricing of EBS is cheaper than uNAS, there are other factors at play. You have multiple variables, not just disk usage.