A split path system leverages the port-level processing capabilities of an intelligent switch to offload the metadata and control information from the data path. Unlike an out-of-band appliance, in which the paths are split at the host, split-path systems split the data and the control paths in the network at the intelligent device. Split-path systems forward the metadata and control information to an out-of-band compute engine for processing and pass the data path information on to the storage device. Thus, split-path systems eliminate the need for host-level agents. Typically, split-path virtualization software will run in an intelligent switch or a purpose built appliance. Providers of split path virtualization controllers are EMC (Invista), Incipient, and LSI Logic (StoreAge SVM).
Array controllers have been the most common layer where virtualization services have been deployed. However, controllers typically have virtualized only the physical disks internal to the storage system. This is changing, though. A twist on the old approach is to deploy the virtualization intelligence on a controller that can virtualize both internal and external storage. Like the in-band appliance approach, the controller processes all three paths: data, control, and metadata. The primary example of this new style of controller-based virtualization is the Hitachi Universal Storage Platform.
Read more about how to deploy storage virtualization in InfoWorld's free PDF report, "Storage Virtualization Deep Dive," including:
- File virtualization
- Three architectual approaches
Read more about virtualization in InfoWorld's Virtualization Channel.