Cisco Nexus 5000 Series Switch Fabric Manager Software Configuration Guide, NX-OS 4.0 (OL-16598-01, June 2008)

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29-2
Nexus 5000 Series Switch Fabric Manager Software Configuration Guide
OL-16598-01
Chapter 29 Performance Manager
Information About Performance Manager
This section includes the following topics:
• Data Interpolation, page 29-2
• Data Collection, page 29-2
• Using Performance Thresholds, page 29-2
• Flow Setup Wizards, page 29-3
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 collection of data for two variables (Rx and Tx bytes) requires a round-robin database (rrd)
file size of 76 KB. If errors and discards are also collected, the rrd file size becomes 110K. The following
are the default internal values:
• 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 collection 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.
Flows are more difficult to predict storage space requirements for, because of their variable counter
requests. Each extra flow adds an additional 76 KB.
Note Performance Manager does not collect statistics on nonmanageable and non-Cisco 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 Fabric Manager 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 Fabric Manager web client Events
tab.