The Roles of CDMI

The proposed SNIA Cloud Data Management Interface standard (CDMI) is intended to address a wide variety of different use cases, as described in the draft SNIA Cloud Storage Use Cases document.

Specifically, CDMI has the several distinct and overlapping design goals:

1. To act as a cloud management protocol for other non-cloud data access protocols, without providing data access.

The use case for this mode of use is, for example, the management of a SAN or NAS fabric allowing the provisioning and specification of data system metadata for opaque LUNs which can be dynamically provisioned programatically, for example, in conjunction with OCCI in a cloud computing environment. In this case, there is no data access via CDMI, only management and accounting access.

2. To act as an cloud management protocol and as a secondary cloud data access protocol to existing cloud and unified storage systems.

The use case for this mode of use is, for example, is to provide consistent management access to existing unified storage systems that provide block, file and object protocols. For example, a Amazon EC2 instance could be run that exposes an S3 bucket through CDMI, manages Elastic Block Storage LUNs, and implements some of the data system metadata functionality.

3. To act as a primary cloud management and cloud data access protocol for next-generation cloud storage systems

The use case for this mode of use, for example, is to enable a superset of cloud data access, manipulation and management functions, and to enable advanced scenarios such as distributed application systems build around cloud storage, cloud federation, peering and delegation. For example, a cloud could provide CDMI access to objects for cloud applications, all while manage file-system views into the object space from remote edge NAS gateways, all while federating together existing enterprise storage and public and private clouds.