Data stored in an ITIL CMDB
ITIL recommends that you store several types of data in the CMDB. Its main purpose is to hold configuration items (CIs) and the relationships between them, which together form a configuration at a particular time or state. ITIL also suggests that the CMDB can hold data related to CIs, such as incident tickets or SLA definitions.
Remember that your CMDB deployment should be based on the needs of consuming applications. Unless and until there is a defined use for a piece of data in your CMDB, ideally that data should not be populated in your CMDB.