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Configuring driver performance settings

Driver settings provide configuration flexibility so you can adjust Double-Take Availability based on your servers, network, and replication requirements. You may want to modify driver settings on both the source and target.

Changing the driver performance settings can have a positive or negative impact on server performance. These settings are for advanced users. If you are uncertain how to best modify the driver performance settings, contact technical support.

1. Start DTSetup.
2. Select Setup tasks.
3. Select Configure Double-Take driver performance.
4. The current driver settings are displayed.
5. Select a driver setting to modify the option.
• Toggle Adaptive Throttling—You can toggle between enabling (true) and disabling (false) Adaptive Throttling. This occurs when kernel memory usage exceeds the Throttling Start Level percentage. When throttling is enabled, operations are delayed by, at most, the amount of time set in Maximum Throttling Delay, thus reducing kernel memory usage. Throttling stops when the kernel memory usage drops below the Throttling Stop Level percentage.
• Toggle Forced Adaptive Throttling—You can toggle between enabling (true) and disabling (false) Forced Adaptive Throttling. This causes all operations to be delayed by, at most, the amount of time in set in Maximum Throttling Delay, regardless of the kernel memory being used. Adaptive Throttling must be enabled (true) in order for Forced Adaptive Throttling to work.
• Set Maximum Throttling Delay—This option is the maximum time delay, in milliseconds, used by the driver during a system delay.
• Set Throttling Delay Interval—This option is the interval, in milliseconds, to check memory usage during a throttling delay. If a delay is no longer needed, the remainder of the delay is skipped.
• Set Throttling Start Level—Throttling starts when disk writes reach the specified percentage. This prevents the driver from stopping replication because memory has been exhausted.
• Set Throttling Stop Level—Throttling stops when disk writes reach the specified percentage.
• Set Memory Usage Limit— This option is the amount of kernel memory, in bytes, used for queuing replication operations. When this limit is exceeded, the driver will send an error to the daemon forcing a remirror of all active connections.
• Set Maximum Write Buffer Size— This option is the maximum amount of system memory, in bytes, allowed for a single write operation. Operations exceeding this amount are split into separate operations in the queue.
6. After you have completed your driver performance modifications, press Q as many times as needed to return back to the main menu or to exit DTSetup.