Cisco DCNM Fundamentals Guide, Release 5.x
Cisco DCNM-SAN Performance Manager
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Configuring Performance Manager

Table Of Contents

Configuring Performance Manager

Information About Performance Manager

Data Interpolation

Data Collection

Using Performance Thresholds

Flow Statistics

Flow Setup Wizards

Creating a Flow Using Performance Manager Flow Wizard

Configuring Performance Manager

This chapter describes how DCNM-SAN is used to monitor and manage a network. This chapter includes the following topics:

Information About Performance Manager

Flow Statistics

Flow Setup Wizards

Information About Performance Manager

This section includes the following topics:

Data Interpolation

Data Collection

Using Performance Thresholds

Creating a Flow Using Performance Manager Flow Wizard

Performance Manager gathers network device statistics historically and provides this information graphically using a web browser. It presents recent statistics in detail and older statistics in summary. Performance Manager also integrates with external tools such as Cisco Traffic Analyzer.

The Performance Manager has three operational stages:

Definition—The Flow Wizard sets up flows in the switches.

Collection—The Web Server Performance Collection screen collects information on desired fabrics.

Presentation—Generates web pages to present the collected data through DCNM-SAN Web Server.

Performance Manager can collect statistics for ISLs, hosts, storage elements, and configured flows. Flows are defined based on a host-to-storage (or storage-to-host) link. Performance Manager gathers statistics from across the fabric based on collection configuration files. These files determine which SAN elements and SAN links Performance Manager gathers statistics for. Based on this configuration, Performance Manager communicates with the appropriate devices (switches, hosts, or storage elements) and collects the appropriate information at fixed five-minute intervals.

Performance Manager uses a round-robin database to hold the statistical data collected from the fabric. This data is stored based on the configured parameters in the collection configuration file. At each polling interval, Performance Manager gathers the relevant statistics and stores them in the round-robin database. This database is a fixed size and will not grow beyond its preset limits.

Performance Manager creates a series of archived data to hold summarized information present in the real-time round-robin database. This archived data is used to generate daily, weekly, monthly, and yearly consolidated reports. In this way, Performance Manager maintains significant historical data without the cost of an ever-increasing database size.

Note You must restart Performance Manager if you change the user credentials on DCNM-SAN Server.

Data Interpolation

One of the unique features of Performance Manager is its ability to interpolate data when statistical polling results are missing or delayed. Other performance tools may store the missing data point as zero, but this can distort historical trending. Performance Manager interpolates the missing data point by comparing the data point that preceded the missing data and the data point stored in the polling interval after the missing data. This maintains the continuity of the performance information.

Data Collection

One year's worth of data for two variables (Rx and Tx bytes) requires a round-robin database (rrd) file size of 76 K. If errors and discards are also collected, the rrd file size becomes 110 K. The default internal values are as follows:

600 samples of 5 minutes (2 days and 2 hours)

700 samples of 30 minutes (12.5 days)

775 samples of 2 hours (50 days)

300 samples of 1 day

A 1000-port SAN requires 110 MB for a year's worth of historical data that includes errors and discards. If there were 20 switches in this SAN with equal distribution of fabric ports, about two to three SNMP packets per switch would be sent every 5 minutes for a total of about 100 request or response SNMP packets required to monitor the data.

Because of their variable counter requests, flows are more difficult to predict storage space requirements for. But in general you can expect that, each extra flow adds another 76 KB.

Note Performance Manager does not collect statistics on nonmanageable and non-MDS switches. Loop devices (FL/NL) are not collected.

Using Performance Thresholds

The Performance Manager Configuration Wizard allows you to set up two thresholds that will trigger events when the monitored traffic exceeds the percent utilization configured. These event triggers can be set as either Critical or Warning events that are reported on the DCNM-SAN web client Events browser page.

Absolute value thresholds apply directly to the statistics gathered. These statistics, as a percent of the total link capacity, are compared to the percent utilization configured for the threshold type. If the statistics exceed either configured threshold, an event is shown on the DCNM-SAN web client Events tab.

Baseline thresholds create a threshold that adapts to the typical traffic pattern for each link for the same time window each day, week, or every two weeks. Baseline thresholds are set as a percent of the average (110% to 500%), where 100% equals the calculated weighted average. Figure 7-1 shows an example of setting a baseline threshold for a weekly or daily option.

Figure 7-1 Baseline Threshold Example

The threshold is set for Monday at 2 p.m. The baseline threshold is set at 130% of the average for that statistic. The average is calculated from the statistics value that occurred at 2 p.m. on Monday, for every prior Monday (for the weekly option) or the statistics value that occurred at 2 p.m. on each day, for every prior day (for the daily option).

Flow Statistics

Flow statistics count the ingress traffic in the aggregated statistics table. You can collect two kinds of statistics:

Aggregated flow statistics to count the traffic for a VSAN.

Flow statistics to count the traffic for a source and destination ID pair in a VSAN.

If you enable flow counters, you can enable a maximum of 1 K entries for aggregate flow and flow statistics. Be sure to assign an unused flow index to a module for each new flow. Flow indexes can be repeated across modules. The number space for flow index is shared between the aggregate flow statistics and the flow statistics.

Generation 1 modules allow a maximum of 1024 flow statements per module. Generation 2 modules allow a maximum of 2048-128 flow statements per module.

Table 7-1 explains the Flow Type radio button that defines the type of traffic monitored.

Table 7-1 Performance Manager Flow Types

Flow type


Unidirectional flow, monitoring data from the host to the storage element


Unidirectional flow, monitoring data from the storage element to the host


Bidirectional flow, monitoring data to and from the host and storage elements

Flow Setup Wizards

The Performance Manager Flow and Performance Manager Setup wizards greatly simplify configuration. All you need to do is select the categories of statistics to capture and the wizards provide a list of flows and links to monitor. You can remove entries if desired, or just accept the provided list and start data collection. Statistics for host and storage links are not associated with a specific port on a switch, so you do not lose long term statistics if a connection is moved to a different port.

Creating a Flow Using Performance Manager Flow Wizard

To create a Performance Manager flow using DCNM-SAN, follow these steps:

Step 1 Choose Performance > Create Flows.

You see the Define Traffic Flows dialog box.

Step 2 Click the drop-down menu in the VSAN field.

Step 3 Choose the list of VSANs provided by the flow configuration wizard.

Step 4 Click the drop-down menu in the Zone field.

Step 5 Choose the list of zones provided by the flow configuration wizard.

Step 6 Click Next to continue to the next window .

Step 7 Choose items in the Possible Flow Pairs area.

The Review Traffic Flows window displays all VSAN flow pairs in the Exisitng Flows for Vsan area.

Step 8 Click Add to create the selected flow.

Step 9 Choose items in the Existing Flows for Vsan area.

Step 10 Click Remove to remove the selected flow.

Step 11 Click Finish to restart the Performance Manager collection.

You see the Confirmation dialog box.

To verify the newly created flow, choose Physical Attributes > End Devices > Flow Statistics. The newly created flows are displayed.