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|Graphic View of Performance:|
Performance Tuner lets you select and consolidate performance data to create throughput graphs.
The main drawback to Performance Tuner in a storage area network (SAN) environment is its dependency on the separate SANView product to get an overall performance summary picture. Performance Tuner is excellent for gathering information about data access times, which is a key metric for SLAs. To view information about HBA and switch port performance, however, SANView must also be installed. These two product views need to be better integrated. For example, viewing alerts and SAN hardware status is accomplished via two separate screens, one in SANView for the overall status of the SAN hardware and one in Performance Tuner for the data access metrics. Ultimately, Softek consolidates the information into a concise view by allowing the graphing of HBAand switch performance directly with the data access metrics (see "Graphic view of performance").
Environment and performance
Our test configuration did not challenge the scalability of Storage Manager. Softek boasts an installation scaling to 500 million files, and others with more than 300 servers each. Softek says the agent's impact on each managed server is generally less than 5% of CPU resources. A bigger issue is the time needed to perform a full environment scan. In this respect, the critical factor is the number of files to be scanned; a large number of small files takes longer than a small number of large files. Organizations with a high file count should be prepared for this process to take the better part of a weekend. The server scans occur in parallel, however, so it's really the largest server file count that determines the total scan time.
After the baseline data is gathered, Space Optimizer gathers and reports incremental sets of data from the agents to the main server. These small sets can be collected in a matter of minutes or hours. Although an administrator can set the data collection process for any interval, once per day is typically sufficient.
SRM tools can easily drown an administrator in data. Performance Tuner's primary strength is its ability to summarize data access statistics into three key, easy-to-monitor metrics: throughput I/O, service index and responsiveness. Similar to a person's heart rate, blood pressure and temperature, these three items provide a quick picture of a storage system's health. Throughput is measured by read/write rates in KB/sec; the service index is the ratio of cached data requests to data requests queued to be read from the disk; and responsiveness is the latency delay in obtaining data. Although Softek provides general guidelines for these metrics (such as a service ratio greater than 70% is a best practice), IT organizations should develop their own data over time. The data that's collected by Performance Tuner for graphing and trend analysis can be used to easily identify deviations from the norm and project future system performance.
Of course, a variety of other statistics can also be monitored, four in particular: Windows cache, physical disk, processor and system times. Each of these includes four to 20 different metrics. History, profile and correlation graphing functions are provided so that an administrator can look back in time, match data access metrics to physical HBA and switch port metrics, and do some predictive analysis. Alerts that trigger when pre-set thresholds are exceeded are easy to set, and can generate SNMP traps, e-mails or displays on the application's alerts screen.
Breadth of features
Performance Tuner offers a solid starting point for storage performance monitoring, upon which Softek can continue to build. Although its name suggests it can provide remedial measures, it offers the features that are most critical to SLA monitoring and management without an onerous administrative overhead.
Softek's biggest challenge will be supporting the myriad devices found in ITenvironments. Even in our modest test configuration, we ran into the problem with the Brocade switch due to an API that was not supported by Windows 2003 Server. Of course, it isn't necessarily required that every component in a SAN be supported, but IT organizations should verify their own configurations prior to purchase with a trial of the system.
This was first published in November 2004