Discovery probes and sensors

  • Release version: Washingtondc
  • Updated February 1, 2024
  • 2 minutes to read
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    Summary of Discovery Probes and Sensors

    Discovery probes and sensors are integral to data collection and updating the Configuration Management Database (CMDB) within IT Operations Management. As patterns increasingly replace probes and sensors, customers are encouraged to create or modify patterns to customize Discovery's capabilities. This information is particularly useful for customers not yet utilizing patterns or those with existing customized probes that remain operational after upgrades.

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    Discovery Phases

    Discovery employs probes and sensors in the initial scanning and classification phases. For the subsequent identification and exploration phases, either probes and sensors or patterns can be utilized. This content specifically addresses probes and sensors.

    How Probes and Sensors Work Together

    Probes collect data from devices, which is then processed by sensors. Both components receive instructions from the ECC queue monitored by the MID Server. Upon data collection, probes send results back to the ECC queue for further processing by associated sensors, which ultimately update the CMDB. Multi-probes and multi-sensors are available to handle complex data scenarios.

    Probe Types

    • Device Probe Types:
      • Windows: Remote WMI queries, shell commands
      • UNIX/Linux: Shell commands via SSH
      • Storage: CIM/WBEM queries
      • Printers: SNMP queries
      • Network gear: SNMP queries
      • Web servers: HTTP header examination
      • UPS: SNMP queries

    Discovery Probe Management

    Most probes and their corresponding sensors come pre-configured with Discovery, minimizing the need for modifications. However, adjustments may be necessary to set parameters for specific behavior or to realign customized versions after upgrades.

    Key Outcomes

    By utilizing Discovery probes and sensors effectively, customers can ensure accurate data collection and CMDB updates, leading to enhanced visibility and management of IT assets across their network.

    Discovery probes and sensors perform data collection and update the CMDB.

    With each release, patterns are replacing many probes and sensors for Discovery. Consider creating new patterns or editing existing ones if you want to customize what Discovery can find. The information on probes and sensors is intended for customers who are not using patterns yet and for customers who already have customized probes that are retained upon upgrade. See Patterns and horizontal discovery for more information on patterns.

    Note:
    For information on Probe to Pattern migration see the knowledge article KB0694477.

    Discovery phases

    Discovery always uses probes and sensors during the first two phases of discovery: scanning and classification. For the last two phases, identification and exploration, Discovery can use probes and sensors or patterns. This topic refers to probes and sensors only. See Exploring Discovery for an explanation of these phases. See Patterns and horizontal discovery for more information on patterns.

    Probes, sensors, and the ECC queue

    The probe collects the information and the sensor processes it. Both get their instructions from the ECC queue. There is a worker job on the MID Server that monitors the queue for work. The monitor checks for any entries where the Queue is output and the State is ready.
    The ECC queue
    The MID Server then processes all the output ECC messages, runs the necessary probes, and returns the probes results to the ECC queue. These results are put in the ECC Queue as input entries.
    Figure 1. ECC queue input
    ECC queue record

    After an entry is inserted in the ECC Queue table, a business rule fires (on insert) that takes that information and runs it through a sensor processor. The sensor processor's job is to take the input data, find any sensors interested in that data, and pass it along to be processed. Those sensors ultimately update the CMDB.

    How probes and sensors work together

    The MID Server launches probes to collect information about a device. The probe sends back information to the sensor to be processed. If the probe has a post-processing script defined, the post-processing script does some data processing on the MID Server before data is sent back to the sensor on the ServiceNow instance. Otherwise the probes sends back all the data collected and the sensor performs this data processing. In both cases, the sensor updates the CMDB.

    A multi-probe is a probe that contains probes. A multi-sensor processes the data from a multi-probe. To process the data from the multi-probe, the multi-sensor contains individual scripts to process the data returned by each probe contained in the Multiprobe, as well as a main multi-sensor script. The individual scripts pass their processed data to the main multi-sensor script.

    The MultiSensor form

    Probe types

    Device Probe Type

    Windows

    computers and servers    		 Remote WMI queries, shell commands

    UNIX and Linux servers

    Shell command (via SSH protocol, version 2). Discovery supports any Bourne-compatible shell.
    Storage CIM/WBEM queries
    Printers SNMP queries
    Network gear (switches, routers, etc.) SNMP queries
    Web servers HTTP header examination
    Uninterruptible Power Supplies (UPS) SNMP queries