Which employees gobble up the most disk space, and why? What's the best way to partition disk space on a storage-area network (SAN)?
Some savvy information technology professionals won't have any trouble clicking on the answers to those questions. They use data from a storage resource management (SRM) tool to identify and prevent capacity or performance problems and to plan for future storage growth.
Unlike tools that handle storage management tasks like backups, SRM tools provide a central view of either physical storage resources such as RAID systems, tape libraries and SAN switches or of logical storage objects such as volumes, files, users, database tables and I/O.
SRM tools fall into 10 distinct application disciplines: asset management, capacity management, chargeback, configuration management, data, device and media migration, events management and alerts, performance management, policy management, quota/space management and removable media management. Most SRM tools combine several disciplines and were designed to work on specific operating systems such as Windows NT or Unix.
Practically all SRM tools offer two levels of functionality: monitoring and alerting features (on-screen, e-mail or paging) provide for day-to-day maintenance of storage resources; reporting and trending features provide for long-term maintenance and planning.
SRM tools usually consist of a service that runs and manages the application from a Web-based central console or graphical-user-interface-based central console, a mechanism for scanning monitored resources, a database that stores collected data from monitored resources and a report generator that can output information in various formats such as Excel spreadsheets or HTML. By supporting Simple Network Management Protocol, an SRM tool can also be administered from network management systems such as Tivoli Storage Network Manager from Tivoli Systems, and Hewlett-Packard's OpenView.
"Some systems administrators haven't a clue about how much storage they have or how it's being used, until it's too late," says John Webster, a storage analyst at Illuminata. "SRM tools can provide all the answers and can ward off an outage."
For example, SRM tools that combine the disciplines of quota and space management, capacity management and performance management let IT professionals know what their disk-space consumption looks like and how to distribute it evenly as a shared resource.
SRM systems' key functions for maintaining day-to-day space consumption and storage performance include the following:
* Determining disk-space usage as a result of thresholds on a user's home directory or a department's folders, getting alerts when thresholds are about to be reached and responding to alerts.
* Running HTML usage reports that enable employees to easily clean out their quota space.
* Setting filters to keep non-business file types such as MP3s and .vbs files from being saved on the network.
* Setting thresholds on I/O performance, getting alerts when thresholds are about to be reached or exceeded and correcting any problems.
* Identifying specific storage resources, such as disk drives that are most likely to fail or are about to run out of space, and taking steps to prevent failures.
* Locating and filling any gaps in backup routines.
SRM systems include the following key planning functions:
* Locating areas of unused space and setting up a policy for reallocating that space through file migration to secondary storage.
* Tracking the growth of files and assessing their implications for file migration, backup and archiving operations.
* Tracking file usage to make decisions about load balancing.
* Identifying growth trends, such as which applications are growing fastest.
* Making decisions about the best way to handle that growth, such as consolidating servers or using a SAN.
Some vendors are planning to enhance their SRM tools with more application disciplines, especially data and device media migration and policy management. Webster says future tools will need to manage multiplatform pools of storage, with views of the storage facility, the attached servers, their operating systems, the file system and the storage internetworking components.
This type of SRM tool could provide a panoramic picture of all storage resources. It could give a systems administrator proof that one port on a SAN switch is causing a bottleneck on an Exchange server or that the slowest disk in a RAID storage system has the most-used table in an Oracle database.
SRM disciplines at a glance
Asset Management tracks and keeps records of all physical storage hardware on a network.
Capacity Management compiles real-time and historical data about physical storage media such as disks and about logical storage resources on a network, such as unused space on specific volumes.
Chargeback acts as an accountant for billing end-user departments for used storage capacity and other storage-related network resources.
Configuration Management determines how to best arrange current physical network storage such as a disk subsystem and SAN switches.
Data, Device and Media Migration enables large amounts of data, such as a data warehouse, to be moved from one system to another. Events Management and Alerts notify systems administrators of errors with storage devices in the network, such as a hard-drive failure, and record all events.
Performance Management provides an ongoing view of application, server and subsystem performance, such as excessive I/O from application servers.
Policy Management specifies rules or policies for managing hardware, files, users, schedules and media.
Quota/Space Management optimises disk usage by assigning specific space allotments to end users and reclaiming wasted space.
Removable Media Management maintains a history of on- and off-site tape, optical storage and other media.