Performance issues when connectivity is not available for Alarm Provider

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If Wonderware Alarm Provider cannot provide alarms to an InTouch system (for instance the module is installed but not in use or there is a communications problem), they will accumulate (up to 250 000 alarms).

The number of alarms it accumulates leads to a large Module Data file on the server which may lead to performance issues when saving and syncing it.

The large number of cached alarms will be causing fragmentation of the memory on the ClearSCADA server as the WonderwareAlarmProvider driver tries to allocate large blocks of contiguous memory every time the module data is saved to disc. This fragmentation of the memory can then lead to a server crash when a large contiguous block of memory can't be allocated.

Symptoms from Status tool/Snapshot log:

• WonderwareAlarmProvider installed (ie in the modules list - it will however always have 0 objects configured, since no ClearSCADA objects are required.

• Module data saves take a long time and may lead to exceptions:

13. Database File Statistics    Id            |File|Flush Pending|Last Save              |File Size|Save Time|Flush Time|Updates|Status    ==============+====+=============+=======================+=========+=========+==========+=======+======    ModuleData    |-   |No           |05/01/2017 23:59:57.937|344.83 MB|16.50 s  |2.632 s   |36     |Ok

• Very large Module Data database buffer:

10. Database BuffersId|Desc                       |Size     |Access Count|Status    ==+===========================+=========+============+===============    0 |Object Fragment (Save DB)  |8.00 MB  |124         |Ok    1 |Object Fragment (Get CRC)  |8.00 MB  |39902       |Ok    3 |Object Fragment (Clone)    |1.00 KB  |2532        |Ok    4 |Object Fragment (Cfg Chng) |1.00 KB  |140         |Ok    5 |Object Fragment (Get Hash) |32.00 KB |648         |Ok    8 |Object Config              |2.00 KB  |2532        |Ok    9 |Object Data                |0 Bytes  |2532        |Ok    10|Object Dynamic             |0 Bytes  |2532        |Ok    12|Template Object Propagation|2.00 KB  |140         |Ok    14|Standby 0 Structure        |16.00 MB |1           |Ok    15|Standby 0 Module Data      |512.00 MB|13          |Ok

We recommend not installing Wonderware Alarm Provider if it is not in use, or disabling it if the Intouch system is expected to be out of commission for an extended period.

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