What the SMI-S standard can and cannot do

SNIA's SMI-S standard promises to simplify management of heterogeneous storage environments, but it won't solve all issues.

By Jim Geronaitis and Ash Ashutosh

To some proponents, the Storage Management Initiative Specification (SMI-S) will solve all storage management problems. Detractors, on the other hand, are extremely skeptical about the promises of SMI-S. The truth is somewhere in between.

The Storage Networking Industry Association (SNIA) has spent significant resources developing SMI-S, which is designed to reduce the cost of storage administration.

SMI-S is based in part on the Common Information Model (CIM), which was developed by the Distributed Management Task Force (DMTF). CIM is a standard that defines the physical and logical structure and behavior of any object to be managed. CIM/XML is a standard method for accessing the modeled objects using the HTTP protocol. Together, the two standards are called Web-Based Enterprise Management (WBEM).

Vendors such as Microsoft and Sun have been shipping CIM-based system management solutions for years as integral parts of their operating systems. Microsoft's WMI and Sun's WBEM Server for Solaris are used to model objects like CPU, memory, processes, applications, and file systems so that management software can interface with and manage operating systems and components consistently.

SNIA used CIM as the basis for modeling storage infrastructures. Using the CIM object and access model, profiles for modeling storage subsystems, switches, host adapters, logical paths, volumes, and security, etc., were created. This storage-specific subset of CIM is SMI-S.

Storage is an integral part of the IT infrastructure and needs to be managed in conjunction with servers, applications, and networks. With SMI-S, users will have CIM-based management solutions for all IT components: servers, networks, and storage.

What does SMI-S do?

SMI-S started out at the bottom of the storage management pyramid: device management. In effect, SMI-S allows for a "Web-services-like" interface to all devices in the storage infrastructure, providing users with a consistent mechanism for device discovery, configuration, event, and status information. In addition, SMI-S provides information about the logical components in the infrastructure: paths, volumes, pools, LUNs, and mappings, etc.

Consider the case of a company that has mandated that all devices in its storage infrastructure be

SMI-S compliant and is using SMI-S-compliant storage management software. The storage administration team is responsible for vendor and device selection. The majority of the team has been trained on the SMI-S model of device structure and behavior for the various storage device models.

As new devices are rolled in, using the standard discovery process the management software instantly detects the structure and behavior of the devices. An asset database tracks this information and classifies the devices into various categories pre-defined by administrator policies. Administrators can use the SMI-S management software to configure devices, provision storage, and enable policies.

As performance and availability issues arise, a consistent end-to-end view assists in isolating and fixing issues, resulting in improved availability.

All this activity is performed independent of specific vendors or device models. The result is significantly lower cost of training administrators in vendor-specific technologies. End-user benefits of adopting SMI-S also include

  • Higher availability due to a standards-based management interface, which minimizes operator errors;
  • End-to-end infrastructure visibility, which increases productivity; and
  • Minimized time spent on vendor- and device-specific management issues, and the potential elimination of non-interoperable management solutions.

Another key benefit of SMI-S is extensibility. For instance, while SMI-S defines a clear profile for how a storage subsystem should appear and behave, it also allows vendors and users to extend the model to make other related information become an integral part of the model. For instance, a user can extend the model of a storage subsystem to include the cost of purchase, date of warranty expiration, installation, and location, using CIM- compliant modeling semantics.

What SMI-S is not

As with any standards, it is more important to define what the specification cannot do, as much as what it can do.

SMI-S defines the structure and behavior of individual devices in the storage infrastructure. It helps in the process of discovery, configuration, event, and status management of individual devices and logical paths between devices.

SMI-S does not solve the problem of hardware incompatibility between devices from different vendors. Compatibility of devices on a storage network is the domain of other standards bodies such as the FibreAlliance and Fibre Channel Industry Association.

SMI-S is evolving, and there are certain areas of storage management that are not covered by the current specification, such as backup and remote replication. While individual device performance capabilities are available, a comprehensive performance management capability will not be available until a later release of the standard.

Also not in the current version is a specification for defining implementations for the various operations of storage management to ensure interoperability of management software.

Most storage vendors have committed to adopting the SMI-S standard. At Storage Networking World in April, more than 20 vendors demonstrated implementations of SMI-S. Expect to see most vendors shipping SMI-S-compliant solutions by year-end.

All good things take time, and SMI-S is no different. SNIA continues to put significant efforts into completing the road map for the specification, but it's up to users to demand SMI-S compliance in hardware and software products so that everybody benefits from wider adoption of the standard.

Jim Geronaitis is a co-chair of the SNIA Interoperability Committee and director of strategic alliances at AppIQ. Ash Ashutosh is the founder and CTO of AppIQ.

This article was originally published on July 01, 2003