The task of collecting the support data is performed by a background CLI task called the record collector. The administrator configures the SDC via the CLI with the commands to be executed on a periodic basis. The record collector always runs in the background and checks if there are records to be collected.

When it is time to collect support data, the scheduler executes the configured sequence of CLI commands and stores the results in a gunzipped (.gz) file on the hard-disk. This file is called an SDR (Support Data Record), and represents a snapshot of the overall state of the system at that time.

Technical Assistance Center (TAC) personnel and local administrators can review the SDRs on-line or by transferring them off the system. They may also wish to investigate the collector state information. The figure below shows system tasks that contain state and counter information. Arrows between tasks and processes represent messenger requests and indicate the predominant flow of data.

Figure 1. SDC Tasks and Processes<

The Support Data Record (SDR) is an ordered set of the CLI support commands' display output that is stored in a stand-alone compressed file. Each CLI support command output is stored in its own record section. The record section is identified by a record section name and its ASCII command syntax. For example, the record section show_version would have a CLI command string of "show version".

The order in which the record section commands appear in the configuration is significant. All of the support record section commands must be configured together as an ordered set. In other words, just specifying one command by itself will result in just that one command output constituting the contents of the entire SDR.

The user may configure a specific set of record sections for the SDR which may or may not include some or all of the default SDR record sections. This configuration is stored in the Global Configuration section of the configuration file. Refer to Configuration Commands (Global Configuration Mode) for more detail on the support record section command.

The show configuration verbose command displays the default support record sections, if the user has not specified any support record sections. If the user has configured support record sections, then the show configuration command displays user-configured support record sections. The support collection schedule configuration also appears in the show configuration output under the Global Configuration section.

At the scheduled time, the Support Data Collector (SDC), if active, runs in the background to collect all the record section commands that have been specified. This information is concatenated as one contiguous output. The output is compressed and stored as a file on disk in the /hd-raid/support/record/ directory.

The periodicity of the SDC is configured by the support collection schedule command under Global Configuration Mode. Once the SDR is stored, the SDC waits the sleep-duration interval specified via the support collection command before collecting another SDR.

The SDRs are stored together in a self-relative set. This self-relative set is called a Support Record Collection. Each individual SDR is identified with a record-id. The record-id of the most recent SDR is always 0 (zero). The next older SDR is record-id 1, and so on, for the number of records in the stored collection. For example, if there are five SDRs, they are identified as SDR-0 through SDR-4.

Figure 2. Support Data Collection Hierarchy

When a new SDR is created, the numbers all increment by one and the newest SDR is given the value of 0. If the total number of records exceeds a configured maximum, then the oldest SDR is deleted.

Using the example above, when the maximum SDR count of 5 is reached, the SDRs continue to be SDR-0 through SDR-4, with the file timestamps indicating that the files are changing over time.

The time interval between collections may vary by several minutes in relation to the specified sleep-duration. This is because the interval specifies the idle time between scheduled collection runs. Since the actual overhead of the collecting process is not included in the scheduled intervals, the time differences between collections includes this non-deterministic amount of time.

The Exec Mode show support collection command displays useful information about the Support Data Collector. The output includes information about when the collector last ran, how long it took to run, when it is scheduled to run again, as well as the number of SDRs currently stored, where they are stored, and how much storage space is being used. Refer to Exec Mode Commands for more detail about this command.

The user can compare the SDRs by examining two or more in sequence. These SDRs are dumped out in their CLI-formatted output display. Comparing the display outputs reveals trends and performance or configuration differences that indicate problem areas.

Once specific record sections have been identified as having problematic characteristics, only the CLI show commands associated with those sections need be monitored and compared to further isolate the problem areas. In addition, individual SDRs may be transferred via system-supported protocols to remote system, or the current collection may be transferred as a set for later analysis.

You may use the collected support data records to view support data chronologically. If the default list and sequence of sections is inadequate for system monitoring, you can configure your own set of record section commands that make up a particular support record.

After configuring the SDR you then configure the sleep-duration interval between record collections and the number of historical records to be retained before being overwritten. By default, configuring this collection information makes the collector mechanism active (if not already active).

After one or more collection intervals have passed, the SDR data becomes available for analysis. The administrator can then use CLI commands to examine the SDR information to perform root cause analysis and trend analysis based on how the data has changed over time. The administrator may decide to transfer the SDRs off the system to be analyzed remotely, for example, by Cisco TAC.

For complete descriptions of the CLI commands discussed below, refer to the Command Line Interface Reference.