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Determining the data threshold at which an enterprise might want to think about public cloud storage is an inexact science. The decision-making process may be affected by the local storage limits and the effectiveness of the caching algorithms with the current crop of cloud storage gateway products, according to Gene Ruth, a research director focusing on enterprise storage technologies at Gartner Inc. in Stamford, Conn. SearchStorage asked Ruth to supply advice on the conditions when public cloud storage makes sense.
It's somewhat gray. In the up to 50 TB range, it could be very attractive because that range fits into the cache sizes or local storage sizes of the cloud gateways available today. When you push beyond that, you're pushing outside the capability of the cache of these gateways, and you're relying more and more on the effectiveness of the caching algorithms to keep the hot data local. You're more exposed to misses, and then you have to go back and read data from the cloud.
When you're in a file-sharing, random type environment, if you get past the cache sizes of the cloud gateways, you start getting into troubling territory because there starts to be a lot of cache misses on a gateway, and your performance will suffer. And the reason you bought the gateway to begin with is to get performance, or what feels like performance, out of the cloud.
If the use case is not dependent on caching algorithms and you're just simply extending the movement of archival data -- data you're not going to touch very often -- into the cloud, then you can get to very large scales of hundreds of terabytes and maybe even petabytes. When you get into the petabyte range, you're talking about a different relationship with the cloud provider because then the provider becomes part and parcel with your IT infrastructure and is more of a partner than just a service.
About the expert:
Gene Ruth is a research director and analyst at research firm Gartner Inc. where he specializes in enterprise storage technologies.
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