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Internal storage clouds
Internal cloud storage runs on dedicated infrastructure in the data center and, as a result, addresses the two main concerns of security and performance, but otherwise offers the same benefits of public cloud storage. Internal storage clouds are usually for a single tenant, even though larger enterprises may use multi-tenancy features to segregate access by departments or office locations. Unlike their public cloud storage counterparts, scalability requirements are more modest, so internal cloud storage offerings are more likely to have traditional storage hardware under the hood. A case in point is HP's CloudStart, which combines HP servers, storage and orchestration software into an internal cloud storage infrastructure. HP CloudStart by itself isn't a private storage cloud offering because it lacks the key element of being service based; instead, it's the enabling infrastructure that could be used by HP, one of its partners or even enterprises to offer it as a fully managed, pay-as-you-go cloud storage offering.
An example of a private cloud storage offering is the Hitachi Data Systems Cloud Service for Private File Tiering. Based on the Hitachi Content Platform (HCP), it resides in the customer's data center but is owned and managed by Hitachi. Besides an initial setup fee, the customer pays for it by usage. Similarly, the Nirvanix Inc. Hybrid Node (hNode) provides a fully managed, pay-as-you-go, internal cloud offering
The hybrid cloud storage model
While internal cloud storage addresses the concerns associated with public cloud storage, it's certainly not the Holy Grail for unstructured data. To start with, these systems aren't designed to leverage existing internal storage infrastructure. The fact they're on-premise means they require data center real estate, electricity, rack space and cooling. Since internal cloud storage runs on dedicated hardware, it won't be able to scale to the degree public storage clouds can. Most unstructured data is static and little used, so it doesn't have to reside on-premise.
This is where hybrid cloud storage comes into play, when traditional storage systems or internal cloud storage are supplemented with public cloud storage. To make it work, however, certain key requirements must be met. First and foremost, the hybrid storage cloud must behave like homogeneous storage. Except for maybe a small delay when accessing data on the public cloud, it should otherwise be transparent. Mechanisms have to be in place that keep active and frequently accessed data on-premise and push inactive data into the cloud. Hybrid clouds usually depend on nimble policy engines to define the circumstances when data gets moved into or pulled back from the cloud.
Today, there are three routes to implementing a hybrid storage cloud:
- Via cloud storage software that straddles on-premise and public cloud storage
- Via cloud storage gateways
- Through application integration
This was first published in January 2011