TAC Vista, Техническое руководство

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2 Basic Demands High Security Systems, Technical Manual
12 (20) TAC AB, Nov 2006
04-00007-01-en
TAC Xenta Protection
Once the TAC Xenta programming is confirmed, it can be locked.
Sending a command from Vista to the Xenta locks and unlocks the
Xenta device. These events are recorded in the Event log. This mode
locks the Xenta from any access via the serial port. This excludes TAC
Menta, Download Wizard and LonWorks network connection through
the serial port on the Xenta. Whether a Xenta is locked or not can be
seen in Vista by viewing the Xenta object. Access rights in Vista are
then set using NT security. Any changes to a Xenta are recorded in the
Historical log. It is recommended that the administrator is the only per-
son allowed to Lock/Unlock and write to the Xenta.
TAC Vista Data Protection
At the TAC Vista level, the Windows access control functionality pro-
tects the data from being changed. This includes protection of the TAC
Vista object databasee as well as the directories and files on the hard
disk drive. The system also protects the system from time change by a
normal user. However, it should be noted that Vista stores trend log data
stamped with UTK time. All user-initiated changes to object data and
alarms are recorded in the event log of Vista.
System Reliability
System reliability is governed by the following operations and func-
tions:
Being able to store data from eight days in the Xenta makes it possible
to recover a failure in the Vista server that stores the data. Having two
Vista servers enables them to monitor each other's operation. A Xenta
unit failure is reported as an offline alarm in Vista. The master Xenta
devices also have UPS backup. This ensures offline alarm reporting to
Vista in the event of failure. The data loss resulting from a permanent
failure to a Xenta unit, where the unit has to be exchanged, is limited to
the rate of reporting log data from the Xenta to Vista.
The data loss resulting from a permanent failure to the hard disk drive
of Vista is limited to the rate of incremental backups made to another
disk.