Initiating Persistent Chat Failover

Persistent Chat failover for disaster recovery relies on SQL Log Shipping as well as setting active Persistent Chat servers. Reference the earlier section “Persistent Chat Disaster Recovery” for possible scenarios. This section outlines the steps required to fail over the Persistent Chat database to the secondary server using SQL Log Shipping, as well as how to configure active Persistent Chat servers for the stretched pool.

The following procedures must be completed from the secondary Persistent Chat Server database. This server will have been the destination for Log Shipping.

1. First, disable SQL Log Shipping. Open SQL Server Management Studio and connect to the database instance where the secondary Persistent Chat server database is located.

2. Open a SQL query window on the Master database and use the following command to disable log shipping:

exec sp_delete_log_shipping_secondary_database mgc

3. Next, bring the backup Persistent Chat database (MGC is the database name) back online. In the same SQL query window that was used before, run the following command:

estore database MGC with recovery

If there are existing connections on the MGC database, you must end these connections by running the following command:

exec sp_who2

Based on the connections previously identified, run the following command to end the connection:

kill <SPID of Connectino>

4. At this point, the SQL configuration is complete and the database will be brought online with the latest data available.

5. Now, Lync Server must be configured to recognize the SQL Server change for failover. On a Lync Server, run the following command in Lync Management Shell:

Set-CSPersistentChatState service:<Persistent Chat Pool FQDN> -PoolState FailedOver

This command allows Lync to use the backup SQL Server as the SQL database for Persistent Chat.

6. Lastly, because Persistent Chat relies on stretched pools, and these pools will have a subset of servers that are not active, a failover scenario requires activating these servers for Persistent Chat service. Reference the disaster recovery design in place, and use the Set-CSPersistentChatActiveServer command to set these servers online. The example that follows assumes a stretched Persistent Chat pool with four active and four passive servers. CHAT1 and CHAT2 are located in Site A, which is the failed site, and CHAT3 and CHAT4 are located in Site B, which is the secondary site being activated.

Click here to view code image

Set-CSPersistentChatActiveServer -Identity <Persistent Chat Pool Display Name or FQDN> -ActiveServers $null
Set-CSPersistentChatActiveServer -Identity <Persistent Chat Pool Display Name or FQDN> -ActiveServers @{Add="CHAT3.COMPANYABC.COM","CHAT4.COMPANYABC.COM"}

The first command will remove all active servers from the configuration; this is the quickest way to adjust those servers in a failover scenario. The second command will add CHAT3 and CHAT4 to the active server configuration.

At this point, the failover for Persistent Chat is complete.