CMDB Patterns for ServiceNow

The Configuration Management Database (CMDB) is the foundation of ServiceNow ITSM, tracking all Configuration Items (CIs) and their relationships.

CMDB Architecture

CI Class Hierarchy

cmdb (Base)
└── cmdb_ci (Configuration Item)
    ├── cmdb_ci_computer
    │   ├── cmdb_ci_server
    │   │   ├── cmdb_ci_linux_server
    │   │   ├── cmdb_ci_win_server
    │   │   └── cmdb_ci_unix_server
    │   └── cmdb_ci_pc_hardware
    ├── cmdb_ci_service
    │   ├── cmdb_ci_service_auto
    │   └── cmdb_ci_service_discovered
    ├── cmdb_ci_appl
    │   ├── cmdb_ci_app_server
    │   └── cmdb_ci_db_instance
    └── cmdb_ci_network_gear
        ├── cmdb_ci_netgear
        └── cmdb_ci_lb

Key CI Tables

Table	Purpose	Key Fields
cmdb_ci	Base CI table	name, sys_class_name, operational_status
cmdb_ci_server	Servers	ip_address, os, cpu_count, ram
cmdb_ci_service	Business Services	service_classification, busines_criticality
cmdb_ci_appl	Applications	version, install_directory
cmdb_rel_ci	CI Relationships	parent, child, type

Creating Configuration Items

Basic CI Creation (ES5)

// Create a new server CI
var ci = new GlideRecord("cmdb_ci_server")
ci.initialize()
ci.setValue("name", "PROD-WEB-001")
ci.setValue("ip_address", "10.0.1.100")
ci.setValue("os", "Linux Red Hat")
ci.setValue("os_version", "8.5")
ci.setValue("cpu_count", 8)
ci.setValue("ram", 32768)
ci.setValue("operational_status", 1) // Operational
ci.setValue("install_status", 1) // Installed
ci.setValue("used_for", "Production")
ci.setValue("owned_by", "sys_id_of_owner")
ci.setValue("support_group", "sys_id_of_group")
var sysId = ci.insert()

CI with Discovery Source

// CI from Discovery
var ci = new GlideRecord("cmdb_ci_linux_server")
ci.initialize()
ci.setValue("name", "discovered-server-001")
ci.setValue("discovery_source", "ServiceNow")
ci.setValue("first_discovered", new GlideDateTime())
ci.setValue("last_discovered", new GlideDateTime())
ci.setValue("ip_address", "10.0.2.50")

// Set classification
ci.setValue("classification", "Production")
ci.setValue("environment", "Production")

ci.insert()

CI Relationships

Relationship Types

Type	Parent → Child	Example
Runs on::Runs	App → Server	ERP runs on PROD-DB-01
Depends on::Used by	Service → App	HR Service depends on SAP
Contains::Contained by	Cluster → Server	Cluster contains Node1
Hosted on::Hosts	VM → Hypervisor	VM01 hosted on ESX01
Members::Member of	CI → Group	Server member of Pool

Creating Relationships (ES5)

// Create relationship between CIs
function createCIRelationship(parentSysId, childSysId, relationType) {
  // Find relationship type
  var relType = new GlideRecord("cmdb_rel_type")
  relType.addQuery("name", relationType)
  relType.query()

  if (!relType.next()) {
    gs.error("Relationship type not found: " + relationType)
    return null
  }

  // Check if relationship already exists
  var existing = new GlideRecord("cmdb_rel_ci")
  existing.addQuery("parent", parentSysId)
  existing.addQuery("child", childSysId)
  existing.addQuery("type", relType.getUniqueValue())
  existing.query()

  if (existing.next()) {
    gs.info("Relationship already exists")
    return existing.getUniqueValue()
  }

  // Create new relationship
  var rel = new GlideRecord("cmdb_rel_ci")
  rel.initialize()
  rel.setValue("parent", parentSysId)
  rel.setValue("child", childSysId)
  rel.setValue("type", relType.getUniqueValue())
  return rel.insert()
}

// Usage
createCIRelationship(appSysId, serverSysId, "Runs on::Runs")

Querying Relationships

// Find all servers an application runs on
function getAppServers(appSysId) {
  var servers = []

  var rel = new GlideRecord("cmdb_rel_ci")
  rel.addQuery("parent", appSysId)
  rel.addQuery("type.name", "Runs on::Runs")
  rel.query()

  while (rel.next()) {
    var server = rel.child.getRefRecord()
    servers.push({
      sys_id: server.getUniqueValue(),
      name: server.getValue("name"),
      ip_address: server.getValue("ip_address"),
    })
  }

  return servers
}

// Find all dependencies of a service
function getServiceDependencies(serviceSysId) {
  var deps = []

  var rel = new GlideRecord("cmdb_rel_ci")
  rel.addQuery("parent", serviceSysId)
  rel.addQuery("type.name", "Depends on::Used by")
  rel.query()

  while (rel.next()) {
    deps.push({
      sys_id: rel.child.getUniqueValue(),
      name: rel.child.getDisplayValue(),
      class: rel.child.sys_class_name.toString(),
    })
  }

  return deps
}

Impact Analysis

Upstream/Downstream Analysis

// Get all CIs affected by a CI outage (downstream impact)
function getDownstreamImpact(ciSysId, depth) {
  if (typeof depth === "undefined") depth = 3

  var impacted = []
  var processed = {}

  function traverse(sysId, currentDepth) {
    if (currentDepth > depth || processed[sysId]) return
    processed[sysId] = true

    var rel = new GlideRecord("cmdb_rel_ci")
    rel.addQuery("child", sysId)
    rel.query()

    while (rel.next()) {
      var parentId = rel.parent.toString()
      if (!processed[parentId]) {
        impacted.push({
          sys_id: parentId,
          name: rel.parent.getDisplayValue(),
          depth: currentDepth,
        })
        traverse(parentId, currentDepth + 1)
      }
    }
  }

  traverse(ciSysId, 1)
  return impacted
}

// Get all CIs this CI depends on (upstream dependencies)
function getUpstreamDependencies(ciSysId, depth) {
  if (typeof depth === "undefined") depth = 3

  var dependencies = []
  var processed = {}

  function traverse(sysId, currentDepth) {
    if (currentDepth > depth || processed[sysId]) return
    processed[sysId] = true

    var rel = new GlideRecord("cmdb_rel_ci")
    rel.addQuery("parent", sysId)
    rel.query()

    while (rel.next()) {
      var childId = rel.child.toString()
      if (!processed[childId]) {
        dependencies.push({
          sys_id: childId,
          name: rel.child.getDisplayValue(),
          depth: currentDepth,
        })
        traverse(childId, currentDepth + 1)
      }
    }
  }

  traverse(ciSysId, 1)
  return dependencies
}

Business Service Impact

// Find all business services impacted by a CI
function getImpactedServices(ciSysId) {
  var services = []
  var processed = {}

  function findServices(sysId) {
    if (processed[sysId]) return
    processed[sysId] = true

    // Check if this CI is a service
    var ci = new GlideRecord("cmdb_ci")
    if (ci.get(sysId)) {
      if (ci.sys_class_name.toString().indexOf("cmdb_ci_service") === 0) {
        services.push({
          sys_id: sysId,
          name: ci.getValue("name"),
          criticality: ci.getValue("busines_criticality"),
        })
      }
    }

    // Traverse upstream
    var rel = new GlideRecord("cmdb_rel_ci")
    rel.addQuery("child", sysId)
    rel.query()

    while (rel.next()) {
      findServices(rel.parent.toString())
    }
  }

  findServices(ciSysId)
  return services
}

CMDB Health & Data Quality

Orphan CI Detection

// Find CIs without relationships
function findOrphanCIs(ciClass) {
  var orphans = []

  var ci = new GlideRecord(ciClass || "cmdb_ci")
  ci.addQuery("operational_status", 1) // Operational only
  ci.query()

  while (ci.next()) {
    var sysId = ci.getUniqueValue()

    // Check for any relationships
    var rel = new GlideRecord("cmdb_rel_ci")
    rel.addQuery("parent", sysId).addOrCondition("child", sysId)
    rel.setLimit(1)
    rel.query()

    if (!rel.hasNext()) {
      orphans.push({
        sys_id: sysId,
        name: ci.getValue("name"),
        class: ci.getValue("sys_class_name"),
      })
    }
  }

  return orphans
}

Stale CI Detection

// Find CIs not updated by discovery
function findStaleCIs(daysOld) {
  if (typeof daysOld === "undefined") daysOld = 30

  var stale = []
  var cutoff = new GlideDateTime()
  cutoff.addDaysLocalTime(-daysOld)

  var ci = new GlideRecord("cmdb_ci")
  ci.addQuery("operational_status", 1)
  ci.addQuery("last_discovered", "<", cutoff)
  ci.addNotNullQuery("last_discovered")
  ci.query()

  while (ci.next()) {
    stale.push({
      sys_id: ci.getUniqueValue(),
      name: ci.getValue("name"),
      last_discovered: ci.getValue("last_discovered"),
    })
  }

  return stale
}

MCP Tool Integration

Available CMDB Tools

Tool	Purpose
snow_create_ci	Create new CI with proper class
snow_cmdb_search	Search CIs with filters
snow_create_ci_relationship	Create CI relationships
snow_impact_analysis	Analyze CI impact
snow_get_ci_details	Get full CI information
snow_run_discovery	Trigger discovery

Example Workflow

// 1. Search for existing CI
await snow_cmdb_search({
  ci_class: "cmdb_ci_server",
  query: "name=PROD-WEB-001",
  include_relationships: true,
})

// 2. Create new CI if not found
await snow_create_ci({
  ci_class: "cmdb_ci_linux_server",
  name: "PROD-WEB-002",
  ip_address: "10.0.1.101",
  operational_status: 1,
})

// 3. Create relationship
await snow_create_ci_relationship({
  parent: appSysId,
  child: serverSysId,
  type: "Runs on::Runs",
})

// 4. Impact analysis
await snow_impact_analysis({
  ci_sys_id: serverSysId,
  direction: "downstream",
  depth: 3,
})

Best Practices

1. Use Correct CI Class - Always use most specific class (cmdb_ci_linux_server, not cmdb_ci)
2. Maintain Relationships - CIs without relationships have limited value
3. Discovery Alignment - Align manual CIs with discovery patterns
4. Operational Status - Keep status current (Operational, Retired, etc.)
5. Unique Identifiers - Use serial_number, asset_tag for uniqueness
6. Service Mapping - Connect CIs to business services
7. Regular Cleanup - Archive retired CIs, remove orphans