Picture Perfect 4.6 Enterprise Edition User Manual - UTCFS Global ...

Chapter 4Managing your network database49Optional software packages, such as Alarm Graphics, Guard Tours, and interfaces to other hardwaresystems, are installed on the subhost because the software of optional packages interacts withdevices installed on a subhost (e.g., input points, readers).Synchronizing the timeDatabase synchronization requires all servers in a Picture Perfect Enterprise system to have thesame time relative to UTC (Coordinated Universal Time). The Network Time Protocol (NTP) processon the nethost is the master time server and is responsible for maintaining the system clocks oneach machine. Each server in an Enterprise system is configured with NTP time synchronizationmechanism. If the times differ, then the subhost adjusts its clock to be synchronized with that of thenethost. If the nethost goes down for a period of time, the subhosts have to wait until the nethostcomes back on-line in order to synchronize their clocks. If a subhost goes down, then it synchronizesits clock when it comes back on-line.Note:The NTP server does not synchronize a drift in time greater than 1000 seconds.Refreshing the databaseIf the nethost goes down, each subhost continues to function normally, with the exception that thedata does not get replicated anywhere. New category records cannot be added to the system, butexisting categories can be added or removed from person records. Records of all tables can beadded, modified, or deleted by workstations connected to the subhosts, and alarms continue to bereported to the alarm monitor on the subhosts. When communication to the nethost is restored, theEnterprise Replication (ER) and refresher programs automatically synchronize the nethost andsubhosts’ global database tables and history tables.If a subhost goes down, the nethost and other subhosts continue to function normally. The microcontrollers connected to the non-operational subhost go into offline mode and continue to grantaccess based on the badge database in the micro. While a micro is offline, up to 5,000 badgetransactions and 2,500 alarm transactions can be stored locally in the micro. Alarms from thatsubhost are not reported to the user because there is no subhost workstation to which they can bereported. Once the subhost is operational, the offline micro transactions are uploaded to the subhost,stored in the history tables, and the history tables are refreshed to the nethost.The database refresher process dbrfsh is used as indicated in the table below:Table 3.Refresh TablesFunction and Table Name Refresh Process Name Refresher DirectionInsert alarm_historyInsert badge_historyInsert operator_hisInsert tour_historydbrfsh -adbrfsh -bdbrfsh -odbrfsh -uSubhost to Host