Understanding Database Connection Timeout (vcDBTimeout) for SQL Server Installer Callbacks (4380251)

When deploying or validating SQL Server instances using Foglight for Databases, you may encounter a scenario where a callback operation (such as grantPrivileges) fails after a specific period, commonly around 80 seconds. This behavior is governed by the vcDbTimeout parameter, which determines the base SQL Server connection timeout. The actual time the system waits for a callback result typically combines this setting with an additional buffer.

Messages like the following may be found int he FMS log file

INFO    [XXXXXXX-0] script.dbwc_mssql_installer.runDBCallbacks - ASP vcDbTimeout = 60000 milliseconds.
INFO    [XXXXXXX-0] script.dbwc_mssql_installer.runDBCallbacks - Waiting for result of callback [grantPrivileges] on agent DBSS-Installer-FGLAMNAME, session 1751501877941, request 1751502061817 for 80 seconds...
ERROR   [XXXXXXX-0] script.dbwc_mssql_installer.runDBCallbacks - Callback failure: no result received from callback [grantPrivileges] on agent DBSS-Installer-FGLAMNAME, session 1751501877941, request 1751502061817

The vcDbTimeout parameter sets the SQL Server connection timeout (in milliseconds) for the installer agent. When the agent initiates a callback operation (for example, to grant privileges), it calculates the total allowable wait time as follows:

• Base Timeout: vcDbTimeout (default 60000 ms, or 60 seconds)
• Buffer Time: A fixed buffer (typically 20000 ms, or 20 seconds) is added to the base timeout to accommodate additional agent processing and network latency.
• Example Calculation:
  total_timeout = vcDbTimeout + buffer
  For example, with vcDbTimeout = 60,000 ms and buffer = 20,000 ms, the total is 80,000 ms (80 seconds).

If the callback operation does not complete within this calculated period, a timeout error is reported in the logs, and the operation is marked as failed.

If you observe callback failures or timeouts at the 80-second mark, consider the following steps:

1. Review and Adjust vcDbTimeout:
   The default value can also be managed via the agent status property: SQL Server Connection Timeout (milliseconds). Increase this value if your environment experiences higher latency or if complex operations require additional time.
2. Understand the Buffer:
   The system adds a fixed buffer (typically 20000 ms) to the base timeout for each callback wait. This is not configurable via the UI, but can be changed in the relevant script if customization is required.
3. Check for Underlying SQL or Network Issues:
   Ensure that SQL Server and network connectivity are functioning correctly, as delays may stem from infrastructure problems.
4. Monitor Logs:
   Review agent and installer logs for messages referencing vcDbTimeout and callback failures to confirm timeout as the root cause.