Easing Management of Storage Devices

FRAMINGHAM (03/20/2000) - As storage area networks become more popular and expand, so grows the diversity of host and storage devices, switches, hubs and adapters deployed across a typical SAN. The challenge is to effectively manage these dynamic SANs and their components without adding complexity and human resources.

The FibreAlliance, a consortium of 40 storage vendors, is defining a Simple Network Management Protocol (SNMP) Management Information Base (MIB) to facilitate SAN management. Members recognize the need to create, maintain and manage compatibility among SAN components.

SNMP has become the management method of choice for SANs, mainly because it is widely supported and can be run out of band. One advantage of out-of-band management is it doesn't rely on the Fibre Channel network. If a network path or component fails, that failure could cut off the connection to an in-band device or management station, preventing a timely repair and restoration of operations. Out-of-band SAN management allows management from any station with an IP address. SNMP can also be run in-band over Fibre Channel.

A goal of the FibreAlliance has been deployment of the Fibre Channel Management Integration (FCMGMT-INT) SNMP MIB. The MIB is a group of parameters, or variables, whose values define and describe the status of a network and its components. The MIB provides a heterogeneous method of managing multiple Connectivity Units across a SAN. (A Connectivity Unit can be any type of addressable component of the SAN, such as a switch or cabinet full of switches.) To ensure the MIB meets the needs of potential users and vendors, the FibreAlliance is working with the Internet Engineering Task Force, which has posted the MIB as a working draft. The MIB is available for review at http://search.ietf.org/internet-drafts/ draft-ietf-ipfc-fcmgmt-int-mib-03.txt.

The FibreAlliance is developing and submitting the MIB to the IETF in phases.

Phase I, submitted September 1999, provides system-level information, and the ability for a net management station to launch third-party management applications on Connectivity Units by accessing the URLs of those devices. This allows those Connectivity Units to obtain information from connected devices for retrieval by the net management station.

Phase II, submitted in December 1999, adds the ability to gather statistics from Connectivity Unit ports, autodiscovery of SAN components and environmental sensors, such as heat. Phase II allows for management frameworks to provide a consistent interface to key SAN components for subcomponent performance management and subcomponent health monitoring, without launching into a component's own device manager. Phase III, planned for submission in April, will add additional versatility.

Storage-management and enterprise-management frameworks are the primary tools to aid IT operations. When using the FCMGMT-INT MIB, these frameworks will let administrators monitor the SAN topology for performance, health, configuration management and growth.

These frameworks typically depict a graphical topology of the SAN, based on information retrieved from the framework server. That server communicates with the SAN devices via agents and SNMP GET commands. In configurations where the SAN device has its own subnetwork, there is a proxy for the SAN devices connected to it. Management framework programs often display color-coded icons for devices and links for the paths, where color identifies problem areas.

Automatic topology discovery is accomplished by sending a Request Node Identification Data (an in-band Fibre Channel protocol) to other Connectivity Units, where the returned IDs are stored in a link table on the SNMP agent in the requesting Connectivity Unit. Each Connectivity Unit's link table contains the IDs of every other device connected to that device. Link tables allow the framework server to gather identifying information from the agent devices. The ability of Connectivity Units to gather topology configuration information and SNMP traps from connected devices greatly reduces the overhead required in the framework server to retrieve information for all SAN components.

Don Swatik is vice president of product management at EMC Corp., a storage vendor in Hopkinton, Mass. He can be reached at swatik_don@emc.com.

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