Store & Forward Buffer (version 26)

Canary's Store and Forward (SaF) service provides local data buffering when the Historian server is offline or when the network connection between the Data Collector and the Historian is interrupted.

How Buffering Works

When the Historian is unreachable, Canary buffers data to local disk. Because data is written to disk rather than held in memory, it persists even if the machine is shut down — no data is lost during a power cycle or restart.

By default, buffered data is stored in the following directory:

C:\ProgramData\Canary\StoreAndForward\

This directory is configured during the initial installation. To change it after installation, follow the steps in the Changing the buffer directory section below.

Disk Space Limit

By default, data will continue to buffer until no more than 4,000 MB of disk space remains. Once this limit is reached, no new records will be buffered. This threshold can be adjusted in the SaF tile under Configuration > Settings.

Once the disk space limit is reached, any new incoming data will be dropped and will not be buffered. Ensure adequate free disk space is maintained to avoid data loss during extended outages.

Changing the buffer directory

To change the buffer directory after installation, complete the following steps in order. Skipping steps may result in data loss or service errors.

1. Ensure there are no current data streams in the SaF service.
2. Stop the SaF service.
3. Update the "BufferDirectory" path in the service configuration file:
   C:\ProgramData\Canary\StoreAndForward\store_and_forward.service.json

   

4. Restart the SaF service.

If the new directory does not exist, it will be created when the service restarts.