The record that needs to be updated by update process is displayed in SM13 with status INIT. If the records stays for longer time in INIT status that indicates the updates are busy or there are no sufficient update processes or update mechanism is deactivate from SM14.
Update handles the record and change the status to "run"
If the update stays long time in status RUN
1. Longer Update
2. Dead Lock (Needs to inform SAP for Program correction)
Updates which could not be updated will be thrown into ERR Status.
1. Update deactivated in SM14
2. Programming problems in LUW
3. Table Space overflow (ORA-1653; ORA-1654)
4. Max Extents reached (ORA-1631; ORA-1632)
5. Archive Struck (ORA-255; ORA-272)
You can also get information regarding SAP BASIS