Storage Resource Management for Windows NT

By Elizabeth M. Ferrarini

Information technology administrators and managers who use Microsoft Windows NT servers will most likely come across Storage Resource Management (SRM) by the end of this millenium. SRM describes the detailed management of specific storage resources and the data stored up on them in a networked system. Michael Peterson, president of Strategic Research Corporation, a research firm specializing in networked storage, says that SRM liberates the NT environment. AIt allows for central administration of a networks= storage resources rather than just administration of a specific process, like backup.@ He uses the analogy that ASRM is to physical storage resources what network management is to routers and hubs, and what systems management is to CPU configuration.@

On the one hand, SRM may be a relatively new term in the NT world. On the other other hand, SRM, a subset of storage management, has been devised and developed over the years on the strategic mainframe platform to help protect the mission critical data stored on these systems.

As critical applications move onto the Windows NT platform, SRM will migrating with the data and grow along with Windows NT. In fact, in its perspective, Software Management Software Expands Beyond Backup/HSM, Dataquest forecasts that SRM software products provided $210 million revenues to vendors in 1997. However, Dataquest predicts that by 2002 SRM products will catapult to generate $1.24 billion in revenues for vendors. Microsoft also is making SRM functionality an integral part of Windows NT 5.0.

SRM fundamentals

Besides protecting data, SRM can reduce overall storage costs. David Hill, a storage analyst with the Aberdeen Group says that organizations need SRM to help them squeeze the most out of their disk storage investment and ease the burden of managing storage. By providing a method of efficiently managing the storage resource, SRM can help determine how to make better use of hard disc and tape capacity, maximize the performance of storage devices, and ensure no loss of data. It may also be possible to anticipate and avoid disc crashes or errors. The results include faster system response, less downtime, and higher availability of data.

The functional benefits of an SRM system include:

• monitoring multiple storage resources across the network to identify and to prevent potential capacity problems.
• setting and monitoring quotas for disc usage so that optimum use is being made of resources.
• identifying units that are most likely to fail enables preventative action to be taken prior to any failure.
• locating and filling gaps in the backup regime to make it more efficient and standardize backup routines to minimize any potential for data loss.

• tracking the growth of files and assessing their implications on migration, backup and archiving operations. Thus the system manager can examine the impact on network traffic and adjust data flows to avoid backup routines overloading the system and optimize performance.
• identifying areas of stale and unused storage and re-allocating this space. This procedure can save capital costs by reducing the amount of new storage required.
• tracking and identifying trends in file usage so that informed decisions can be made about load balancing. Spotting growth trends to plan for future capacity and to justify new storage purchases.

Major components and functions of the SRM system

A core administration application controls and monitors server and client activities, defines storage management policies, and sets up schedules for operations. This component can run from anywhere in the network to manage the system. Additional backup and archive and components and hierarchical storage management functions may work in conjunction with the SRM software. Some systems will have an applications programming interface (API), which enables the creation of additional functions required to manage particular devices or types of data, such as databases or multimedia that are not always met by common file systems.

File migration

One of the most valuable functions of the SRM system includes the management of disc space. Usage gets maximized as dead areas are identified and infrequently used files are moved to secondary resources. This sounds very much like Hierarchical Storage Management functionality and, indeed, the SRM system may incorporate HSM software, but it goes no further in SRM.

HSM systems identify trends in the usage of disc areas and data types. The usage or non-usage of system areas can be identified and a balance can be stuck between the use of local resources and centralized storage. Administrator intervention ensures that the migration policies do maximize the use of space and balance the distribution of data efficiently, but the migration and recall process will be invisible to the user. As with any HSM system, when required, files get transparently recalled to the local file system for standard access. Storage management policies indicate how much free space to maintain on the local system, which files are candidates for migration, what backup copies should also exist for migrated data, and what storage hierarchy the migrated data should be placed in.

Additionally, the management of storage areas can now extend to avert any problems with capacity limitations. In some SRM systems, when capacity reaches it limit, migration of the most suitable files - decided upon by user-defined policies - will take place to free space so that normal operations can continue.

Space management, however, needs to be tuned for the requirements of the applications on the system. For example, a data analysis application that collects some statistics on data, which was from the previous month, may require access to files that have already been migrated. The analysis program will need to read the data files once, and in a sequential manner, making no amendments or additions. This application can, therefore, be set to run in the most efficient way - reading the files into memory but not recalling them from the secondary medium to local storage. This avoids unnecessary writes to local disc and a further migration at a later stage.

Data Backup and Archiving

Most systems make it possible to set-up specific operational parameters for data backup and archiving but in functional terms, these operations are the same. Backup and archive perform operations can be run in parallel with standard application access. Backup and archive processes are typically scheduled, but can be initiated by system events or in an ad-hoc manner. System administrators can dictate, through the policy functions of the system, whether exclusive access is required for a file to be backed up or archived, or whether shared access is permitted.

Considerations for Selecting an SRM System

Overall functionality should determine help the selection of an SRM system. Other factors have to be considered as well. Performance needs to be considered in light of all the available system resources. SRM systems must meet data availability requirement. Factors, such as data rates for a given storage device and sustainable throughput rates for the network infrastructure, define the rates of data delivery. The use of fibre-channel arbitrated loop systems within a storage area network would make for a desirable platform for an SRM system.

The inherent capabilities of the SRM system need to be considered. SRM systems deploy a wide range of techniques to ensure that data is handled in an efficient manner at the appropriate level.

Scalability could also be important. To achieve this, SRM systems need to support multiple concurrent operations and possibly multiple servers, as well so that it is possible to balance loads efficiently and to create a system hierarchy. Interoperability with existing systems may also be a

consideration. NT may be the main platform, but can other resources running under other systems also be managed - at the server and the local level?

Since the reliability and availability of the system are crucial, the following functions need to be considered:

• replicating of data and using multiple physical storage volumes
• maintaining off-site data vaulting
• protecting meta data (data about data) through mirrored databases and full backup/recovery operations
• dynamically setting and updating all operational values without having to shut down the system

Support for mobile computing must also be considered and, increasingly, there is a requirement for remote management of resources. What is the potential for using the SRM system over the Internet or in a network-computing environment?

Integration with systems management

An SRM system can fit into the existing or planned systems management infrastructure and, in particular, the network management. To do this, the SRM system needs to have compatibility with the network management system and use the same protocols so that it can alert the system to error conditions. To this end, the SRM system should be compatible and support for SNMP, RMON or other protocols. In the NT environment, the SRM system may also make use of Open Database Connectivity (ODBC) modules or through the Distributed COM system.

Microsoft builds SRM into NT

Microsoft is building SRM into Windows NT 5.0 through the Microsoft Removable Storage Manager (MRSM). It enables Windows NT administrators to manage tape, optical, and CD-ROM media, drives, and robotic libraries from different manufacturers through a common graphical interface. MRSM will also enable applications like backup and recovery, HSM, and document imaging, to share the same tape and optical drives and libraries.

Elizabeth M. Ferrarini, HighGround Systems, 800-395-9385, eferrarini@highground.com