STORAGE MANAGEMENT: Using CIM and WBEM for management

SNIA recently demonstrated storage management using the Common Information Model and Web-Based Enterprise Management standards.

By Andrea Westerinen

Click here to enlarge image

A few months ago, disk storage and operating system vendors cooperated to manage seven diverse storage arrays and displayed all the management data via Web pages. The primary goal of the demonstration was to prove that storage management, using a common data model and eXtensible Markup Language (XML) style sheets, was possi-ble with existing standards and technologies.

The demonstration was based on management infrastructures from Microsoft and Sun Microsystems.

The management demonstration was the brainchild of the co-chairs of the Disk Resource Management (DRM) Working Group of the Storage Networking Industry Association (SNIA). John Tyrrell of IBM and Mike Dutch of Hitachi and their team had been struggling with the problems of enterprise-wide storage resource management. Their charter was to define interfaces to enable cross-vendor asset, performance, configuration, fault, policy, and capacity management.

Click here to enlarge image

In this demonstration, only a small piece of the management puzzle was addressed. The scope was defined as a storage system's physical inventory and assets, with additional information available on the total physical capacities of the systems. Vendors participating in the demonstration included Clariion, Compaq, EMC, Hitachi Data Systems, IBM, Microsoft, StorageTek, and Sun. Storage arrays varied in size from a set of disks in a workstation to a mainframe-sized storage cabinet.

The demonstration focused on taking vendor-specific storage, access mechanisms and instrumentation, and publishing data using the syntax and semantics of the Distributed Management Task Force's (DMTF) Web-Based Enterprise Management (WBEM) specification. Data was published from vendor-supplied "providers" to Common Information Model (CIM) infrastructures developed by Microsoft and Sun. The semantics of the data were defined by the CIM standard, and XML was used as the syntax for exchanging data and requests with the management infrastructures. Data was displayed using XML style sheets, accessed from a pre-defined Web site, using a standard laptop and phone line.

Management in a heterogeneous environment typically requires special-purpose or vendor-specific management software, using data acquired from several sources such as device drivers, vendor-specific agents, or sometimes proprietary SNMP instrumentation.

This translates into storage management costs that can be 10 times higher, per year, than the cost of hardware acquisition. Unfortunately, this picture is not different for servers or network devices.

The manageability demonstration showed that CIM is a viable way to organize management data and that XML and HTTP provide a practical means for Web-based and interoperable management. The demonstration also tested the WBEM plumbing and validated the CIM object management infrastructures from Microsoft and Sun.


Great functional support exists today in storage area networks (dedicated networks for de-coupling storage from servers and clients) and network-attached storage (abstracting storage as file access services). The benefits of storage networking include:

  • Sharing of heterogeneous resources among heterogeneous systems
  • Storage consolidation
  • Ability to separate storage traffic from LAN traffic
  • Independent scaling of storage

Many vendors are offering product bundles that are verified in internal interoperability labs and at "plugfests." But more is needed in the areas of management and interoperability of higher-level services (above the physical interconnect).


WBEM is a DMTF initiative. It represents a set of technologies to enable the interoperable management of an enterprise. WBEM consists of

  • CIM
  • An XML Document Type Definition (DTD) defining the tags (XML encodings) to describe the CIM Schema and its data
  • A set of HTTP operations for exchanging the XML-based information

Since XML is only a data description language, and HTTP is only a transport, these technologies need to be brought together with an underlying information model-the conceptual view of the enterprise. That underlying information model is CIM.

CIM abstracts the managed environment. It attempts to unify and extend the various instrumentation and management standards, such as SNMP and the Distributed Management Interface (DMI) for PCs. CIM accomplishes this through the use of object-oriented constructs and design techniques.

The CIM Schema provides a way to organize management information without requiring a particular instrumentation protocol or data repository format. For example, SNMP data can be placed into a CIM object hierarchy that is implemented as a relational database, as an object database, or as an LDAP directory. To retrieve data, a client issues the correct HTTP operations and references the data using XML encodings.

The object-oriented nature of the CIM Schema supports the following capabilities that other "flat" data models (such as SNMP) do not:

  • Object abstraction and classification reduces complexity by defining high level and fundamental concepts (the "objects" being managed).
  • Inheritance allows detail to be added to the management objects, placing information and complexity at the right levels in the object hierarchy.
  • Dependency, component, and connection relationships are defined as "associations." These are independent objects with their own semantics, inheritance hierarchy, and properties. Before CIM, management standards captured relationship information in multi-dimensional arrays or cross-referenced tables.
  • Standard, inheritable methods define and abstract object behavior.

Areas addressed by CIM span the managed environment. The goal is not to address a single problem domain (such as networking) and the individual entities (such as switches or hubs) as independent sources of information, but to describe the configuration, events, and capacity of the enterprise using a single information model, a single syntax, and a single definition of high-level semantics.

High-level semantics in CIM are defined in the "Core Model." Various concepts (and objects) are defined, such as:

  • Product-a unit of acquisition
  • System-a top-level object in an enterprise, viewed as an identifiable functioning whole, but assembled from component software and hardware
  • Device-any abstraction of hardware
  • Service-any functionality offered to and accessed by clients
  • Service access points-the management of access to Services and the mechanisms of access

However, high-level abstractions are not enough. To get into the details of particular problem domains such as systems, networks, users, policies, and applications, the DMTF has defined "Common Models" that subclass from the Core Model and extend it. The Common Models are defined cooperatively, and overlap and build on each other. The individual Common Models are interrelated via associations and sometime subclass from each other, all starting with the same Core Model object and concepts.

SNIA works within the DMTF as an Alliance Partner. The SNIA Work Groups designed the Storage Library model for inclusion in the latest release of the System and Device Common Models. Other SNIA teams recommended clarifications and additions to the existing storage constructs in the Device Model. And work is progressing to bring additional proposals to the DMTF in the areas of WBEM discovery and security, and the modeling of capacity planning, media management, movement of storage data for backup and recovery, and storage configuration services.

SNIA's management demonstration built on concepts defined in CIM's Core Model and the Physical Common Model. The demonstration started with a CIM_Product object at a particular CIM_Location, moved to physical packaging (subclasses of CIM_PhysicalElement) and the placement of CIM_Cards in CIM_Slots, and then onto subclasses of CIM_PhysicalCapacity. Standard CIM classes were instantiated and related using CIM-defined associations.

End users to benefit

What can IT managers expect? SNIA will be publishing educational material, guidelines, and "best practices" documentation. The organization is working to extend and define new management schemas (for submission to the DMTF); to define new Fibre Channel network services (for submission to ANSI, American National Standards Institute); to extend protocols for better performance of file systems (for submission to the IETF, Internet Engineering Task Force); to put new APIs in place for snapshot and point-in-time copy of data; and to address the operation and management of storage data movement (as the underpinnings of backup or disaster recovery). SNIA is also ramping up its interoperability efforts.

What should IT managers do? The bottom line is to get involved in the SNIA organization and other standards work. For example, both the DMTF and the SNIA have industry advisory councils. These councils are in place not to drive the technical details of the standards, but to get technical and educational requirements into the Working Groups. After all, IT managers need to participate in standards developments and to understand the standards efforts enough to specify the correct ones in future products.

Andrea Westerinen is technical director of the Storage Networking Industry Association (SNIA). www.snia.org.

History of the demonstration

SNIA's Disk Resource Management (DRM) group co-chairs, John Tyrrell and Mike Dutch, were introduced to the DMTF's work in April 1998, at a joint DMTF and SNIA meeting, as the first versions of the CIM storage model were being released. The group studied it, and started to recommend "profiles," that is, sets of objects and relationships necessary to describe storage entities such as a disk-drive package or a disk-array cabinet.

In March 1999, the DRM group decided to put their profiles and the existing WBEM infrastructures to the test in a live demonstration. The goal was to assess the completeness of the CIM Schemas and to gain experience with and establish the maturity of the supporting infrastructures.

In doing their analyses, the DRM group found that some concepts were missing from the CIM Schemas. They brought recommendations back to the DMTF for incorporation into CIM releases in June 1999.

The DRM group intends to keep developing standard "profiles" for management, and to expand the demonstration. Other SNIA Work Groups are getting involved to integrate the management of their problem domains.

For example, the next demonstration (scheduled for the Storage Networking World conference in April, in Palm Spring, CA) will include additional management functions (going beyond asset information) and support for cartridge library and Fibre Channel-specific data and profiles. The ultimate goal is to enable the storage industry to release CIM-based instrumentation and management products into commercial products, starting this year.

The storage industry's work in improving management and interoperability is only beginning. For example, more standardization and the definition of interoperability tests at the storage services level are needed to begin reducing IT costs. Addressing these areas (manageability and interoper ability) are primary goals of SNIA.

This article was originally published on January 01, 2000