Consistent distributed storage communication protocol semantics in a clustered storage system

摘要

Consistent distributed storage communication protocol semantics, such as SCSI target semantics, in a clustered storage system are disclosed. The system includes a mechanism for presenting a single distributed logical unit, comprising one or more logical sub-units, as a single logical unit of storage to a host system by associating each of the logical sub-units that make up the single distributed logical unit with a single host visible identifier that corresponds to the single distributed logical unit. The system further includes a mechanism to maintain consistent context information for each of the logical sub-units such that the logical sub-units are not visible to a host system as separate entities from the single distributed logical unit.

主权项

1. A non-transitory computer readable medium storing computer-executable instructions, comprising:
instructions to implement a storage operating system on a computing device, wherein the instructions implement the storage operating system as a node in a clustered storage system; instructions to implement a protocol target instance that interacts with at least a peer protocol target instance on a peer cluster node of the clustered storage system to implement a distributed logical unit that performs data storage protocol processing for a host, the distributed logical unit being a distributed object that includes a set of target sub-devices hosted on one or more nodes in the clustered storage system, wherein the protocol target instance presents the distributed logical unit as a single target device to the host, the distributed logical unit being a representation of a physical data storage or an abstraction of physical data storage on which data in the clustered storage system is stored; instructions to implement a target sub-device having at least a logical sub-unit therein, the logical sub-unit being part of the distributed logical unit; instructions to implement a logical target port to provide routing for a command or task management function from the host to an appropriate logical sub-unit in the distributed logical unit, wherein the logical target port references a physical port of the computing device; instructions to process, at the logical sub-unit, the command or the task management function to thereby modify context information of the distributed logical unit, the context information comprising data storage or data state information of the logical sub-unit; instructions to, in response to processing the command or the task management function, notify a peer logical sub-unit implemented by the peer protocol target instance that the context information is modified; instructions to implement an instance of a global task set for the logical subunit to queue the command or the task management function from the host that modifies the context information; and instructions to coordinate entry of a first command or function into the instance of the global task set such that the instance of the global task set is consistent with a peer instance of the global task set implemented on the peer logical sub-unit.