FAIS spurs storage applications

A new generation of storage volume management and data-movement applications are moving from servers and storage subsystems into networks to enable centralized management and more-scalable storage-area network architectures. To achieve the required level of performance, fabric-based storage applications are split into hardware-accelerated functions (data path) and non-hardware-accelerated functions (control path). Hardware-accelerated functions are offloaded to intelligent SAN platforms such as switches or storage appliances. But the storage applications and intelligent SAN platforms use proprietary APIs, limiting migration between vendor platforms.

To ensure smooth implementation of intelligent SAN infrastructures, the T11.5 Task Group of the ANSI T11 Committee created a working group to define a standard API between control-path and data-path functions implemented in storage management applications and intelligent SAN platforms. Fabric Application Interface Standard (FAIS) should accelerate product development and give users more choices.

Splitting control-path functions from data-path functions lets the storage and data management applications delegate processing of all data-path functions to the intelligent SAN platforms, while maintaining the control-plane functions. By providing the required processing capabilities, intelligent SAN platforms are paving the way for network-based deployment of storage and data management applications.

FAIS is based on a client/server model, where the storage application acts as the client and the intelligent SAN platform acts as the server. This decouples the implementation intricacies of intelligent SAN platforms from the development of storage applications.

FAIS provides the API to access the data-plane functionality an intelligent platform supports. The API is built on an object model, where various storage elements are represented as managed objects. For example, SCSI initiator, SCSI target, logical units and their virtualized counterparts are modeled as objects. The storage application and the intelligent SAN platform interact by exchanging information through these objects. By standardizing the data structures for the various objects and the functions to access them, FAIS provides a high level of independence from the implementation specifics of an intelligent platform.

FAIS will define:

• Operational model (client/server model).
• Object model (storage elements as objects) and object definitions.
• Function calls (API) to interact with the defined objects.
• Software structures (libraries) and behavior (synchronous and asynchronous modes).

FAIS will enable the storage applications to use a standard API to perform all the functions of a SCSI initiator and/or a SCSI target. It also will enable high-availability configurations and management of the I/O acceleration functionality supported by the intelligent SAN platforms.

Services supported by APIs include:

• Front-end services: For processing requests and events that arrive at the FAIS platform from the front end such as SCSI discovery.
• Virtualization services: For volume management, including storage pooling, the ability to control and manage access permission on independent volumes and the ability to implement other key storage functions such as mirroring and striping.
• Back-end services: For discovery and management of storage resources connected to the back end of the FAIS platform, which includes issuing commands to these devices, and handling errors and events received from them.

The working group developing the FAIS standard expects to release a first draft of the specification during the second half of this year. The standard should significantly speed the deployment of storage applications in the fabric and give users a wider choice of intelligent SAN platforms and applications.