Monitoring and Graphing Performance

This section explains how to:

• View metadevice statistics

• Graph metadevice statistics

• Set grapher options

Performance Monitoring vs. Performance Analysis

DiskSuite Tool gives you the capability for simple performance monitoring of metadevices and physical disks. The goal of performance monitoring is to maximize system performance by making small changes while maintaining data availability. Performance monitoring assumes that you are using a given configuration that you cannot easily or often reconfigure.

Performance analysis, on the other hand, aims to maximize system throughput or minimize latency by trying out various configurations until the "best performance" is achieved. Performance analysis assumes that you can set up multiple configurations and collect a different set of data from each configuration. This requires a different methodology and set of tools to cover such tasks as device configuration, file system management, data collection, test load generation, and the like.

The performance monitoring capability within DiskSuite Tool is best suited for the day-to-day operation of DiskSuite in spotting performance problems associated with hot-spots and bottlenecks. This enables you to monitor general performance trends, look for abrupt changes, and compare data collected for different parts of a configuration. For example, while monitoring a RAID5 metadevice, you might notice one column (slice) that shows much more I/O than the other columns. By moving that column to another disk, you are able to better balance the I/O for the entire metadevice.

Preliminary Information for Performance Monitoring and Graphing

• DiskSuite Tool displays a subset of the raw statistical data provided by the kstat(3K) interface. (Refer to the kstat(3K) and iostat(1M) man pages for more information.)

• Because DiskSuite Tool uses the kstat interface, it can only present disk-level statistics, not slice-level.

• You can drag and drop objects from any of DiskSuite Tool's windows to the Statistics Graphs window. This includes the Metadevice Editor canvas, the Objects list, the Slice Browser window, and the Disk View window.

• When you drag a slice to the Statistics Graphs window, you effectively drag the entire disk. You cannot get slice-level statistics.

• State database replicas, hot spare pools, and individual slices cannot show statistics.

• Tip: A good way to start using statistics is by first looking at the metadevice's Load value. Next, examine whether reads or writes seem responsible. You can then add the disks themselves that make up the metadevice and view each disk's load.

• In general, the raw throughput data and the Load value seem to be the most useful values to watch over time.

How to View Device Statistics (DiskSuite Tool)

Use this task to display a device statistic sheet that shows a "snap-shot" for the current values of the statistical variables.

1. Select an object from either the Metadevice Editor window or the Disk View window.

   The MetaDB object, hot spare pools, and slices are not able to show statistics.

2. Select Statistics from the Object menu in either window to display the Device Statistics window for the object.

   For reference information on the Device Statistics window, see the online help.

3. To view a new snap-shot of statistical information, click Update.

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   Note -

   DiskSuite Tool displays a separate Device Statistics window for each disk selected in the Disk View window. Thus, if you select a controller or tray with many disks, you'll see as many separate Device Statistics windows as disks selected.

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How to Graph Device Statistics (DiskSuite Tool)

Use this task to display instantaneous statistical information in the form of a graph for a device.

1. Select Statistics Graphs from the Browse menu in the Metadevice Editor window to display the Statistics Graphs window.

2. Drag an object from either the Metadevice Editor window or the Disk View window to the Statistics Graphs window.

   The Statistics Graphs window will display statistics and a blank area for the graph of the object. The MetaDB object, hot spare pools, and slices are not able to graph statistics.

3. Choose the statistical information to be graphed.

   The Statistics Graphs window contains two "y-axis" (two vertical scales) of statistics. Thus, you can graph any two of the types of statistics available:

   Ops/sec - The number of disk I/O operations per second, measured in terms of reads, writes, or as a total.

   Kbytes/sec - The number of kilobytes of disk I/O, measured in terms of reads, writes, or as a total.

   Load - The disk load measured either as the percentage of time busy, or as a wait queue, which represents the average number of transactions waiting for service.

4. When done using the Statistics Graphs window, select Put Away from the All Graphs menu.

   If you do not put away a device, the Statistics Graphs window automatically includes it the next time it is opened.

How to Add Devices to the Statistics Graph Window (DiskSuite Tool)

1. Select Statistics Graphs from the Browse menu in the Metadevice Editor window to display the Statistics Graphs window.

2. Drag an object from either the Metadevice Editor window or the Disk View window to the Statistics Graphs window.

   The Statistics Graphs window will display statistics and a blank area for the graph of the object. The MetaDB object, hot spare pools, and slices are not able to graph statistics.

3. Refer to Step 3 in the "How to Graph Device Statistics (DiskSuite Tool)" task ("How to Graph Device Statistics (DiskSuite Tool)").

How to Remove Devices From the Statistics Graph Window (DiskSuite Tool)

1. Select Statistics Graphs from the Browse menu in the Metadevice Editor window to display the Statistics Graphs window.

2. To remove a single device, select it and click the Put Away button.

   The Statistics Graphs window clears the device from the list.

3. To remove all devices, select Put Away from the All Graphs menu in the Statistics Graphs window.