Thursday, November 15, 2012

Bandwidth costs for Cloud Storage

Our analysis of the costs of cloud storage assumes that the only charges for bandwidth are those levied by the cloud storage service itself. Typically services charge only for data out of the cloud. From our privileged viewpoint at major universities, this is a natural assumption to make.

At The Register Trevor Potts looks at the costs of backing up data to the cloud from a more realistic viewpoint. He computes the cost and time involved for customers who have to buy their Internet bandwidth on the open market. He concludes that for small users cloud backup makes sense:
I can state with confidence that if you have already have a business ADSL with 2.5Mbps upstream and at least a 200GB per month transfer limit (not hard to find in urban areas in most developed nations) then cloud storage for anything below 100GB per month will make sense. The convenience and reliability are easily worth the marginal cost.
For his example large user at 15TB/mo with a 100Mbit fiber connection, the bandwidth costs from the ISP are double the storage charges from Amazon, for a total of $4374. And recovery from the backups would cost about as much as a month's backup, and would take a month to boot. That simply isn't viable when compared to his local solution:
The 4TB 7200 RPM Hitachi Deskstar sells for $329 at my local computer retailer. Five of these drives (for RAID 5) is $1,645; a Synology DS1512+ costs $899. A 10x10 storage unit is $233/month, and the delivery guy costs me $33 per run. So for me to back up 15TB off-site each month is $2,800 per month.
Of course, in many cases libraries and archives are part of large institutions and their bandwidth charges are buried in overhead. And the bandwidth usage of preservation isn't comparable to backup; the rate at which data is written is limited by the rate at which the archive can ingest content. On the whole, I believe it is reasonable for our models to ignore ISP charges, but Trevor's article is a reminder that this isn't a no-brainer.

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