The BSM approach is well described in ITIL (Information Technology Infrastructure Library) practices.
Also, ITIL practices describes use of technology similar to uCMDB (Universal Configuration Management Database).
The HP implementation of BSM includes the uCMDB into the BSM installation, and HP has named it "RTSM" (Run-time Service Model).
uCMDB is one of the fundamental things in both ITIL practices and HP BSM itself as a realization of this practices.
As a reflection of the IT infrastructure, the HP implementation of the uCMDB uses not a record concept but topology concept.
The HP chosen usage of the uCMDB uses it’s own query language, known as TQL (Topology Query Language).
Topology-based structure of the HP uCMDB has it's own specifications and as a part of this, a mechanism called 'reconciliation' is used.
As a connecting link between all software components of BSM, the uCMDB must store information from a lots of sources.
For example, HP RUM and HP NNMi both can update a topology of a network (u which is actually a uCMDB structure).
For example, take a situation where both RUM and NNMi have discovered the same node and created it in the uCMDB (as a separate products they separately coordinated, only via the uCMDB).
There will have duplicate information on the same node and that needs to be avoided. Only one single record is needed, because actually there is only one machine in network.
In this situation 'reconciliation' of these nodes will take place. The mechanism of 'reconciliation' has it's own set of rules use to merged these two nodes.
For example, the simplest rule is when a couple of transactions have same name and same BTF. All of this transactions would be merged into one. Seems logical.
The most important thing to realize is that when 'reconciliation' occurs, is that the merged element will have new ID (actually, it would be not new, but it would be one of the old ones).
Looking at this situation from EUM (End User Management) point of view. As a part of HP BSM, EUM itself is integrated into BSM with the uCMDB as well.
EUM has it's own storage of information in management schema. All of this information is connected to CMDB model via IDs of the uCMDB elements.
When 'reconciliation' takes place and an ID of an element is changing, the connection between EUM and CMDB CI's will be broken.
EUM tries to find information about corresponding elements in CMDB depending on the old IDs. In this case there is a 'broken model'.
In some rare cases it is possible to restore the previous structure, but due to complexity of the EUM data model this is a very hard task even in case if only 1-2 elements have been reconciled.
The worst case of reconciliation is a reconciliation on the application level. In this case two applications are merged into one (all the BTFs and transactions of both applications will be connected to another).
To avoid reconciliation, one will need only to be careful when working with names or grouping of CIs.
Most of the time, HP support cases about reconciliation issues are logged because of manipulations of name changes.