In the event that you must restart an existing mirror server application, e.g., for upgrading or moving the installation, please review the following recommendations and information. The recommendations will ensure that the restart time for the mirror server will be as short as possible.
Stopping and starting a mirror server does not require that you stop the main server. During the time that the mirror server is down, users and any API applications will continue to work against the main server. Any write operations made during the mirror's downtime will need to be sent to the mirror server as described in Introduction to the SystemWeaver Mirror Server Solution as part of its restart process. Therefore, it is recommended that you:
- Schedule the mirror downtime for when there is low event activity, and
- Send a notification out to users running API applications that perform large data updates asking them to pause their applications during the downtime.
Restarting the Mirror Server
When you are ready to restart the mirror, simply start the server application via the Windows service.
The main server will indicate "Reading journal..." as shown in the main server swServer log snippet below:
The mirror server first performs initialization and then checks the mirror's cache to make sure it is in sync with the main server as shown in the example mirror swServer log below:
If many events (write operations) have occurred while the mirror server was down, you will start to see "Updating cache" entries for every 10,000 events being written to the cache file:
This is an indication that it is making progress. Let it continue to run. You can also view in the main server's swServer.log approximately how many more transactions are left to read to the cache file.
Once it has finished updating the cache, the mirror swServer log will show the following when the mirror is up and running:
Confirm a login to the mirror server using a client.
|Note: If a mirror restart is taking a very long time due to a high number of missed events, an alternative is to create a new cache file for the mirror either from a new database backup, or from the live database, but the later requires stopping the main server.|
Automatic Reconnect to Main Server
As of release R37, if a mirror server loses connection to the main server, either because of network problems or if the main server is restarted, the mirror server will attempt to reconnect automatically every 30 seconds. As soon as the main server can be reached again, it will reconnect. This means that there is no longer a need to restart a mirror server if a main server is stopped.