Configure High Availability for Persistent Chat

High Availability for Persistent Chat Overview

High Availability (HA) for Persistent Chat is an optional feature that you can deploy if you are using Persistent Chat rooms and you have system redundancy configured with Presence Redundancy Groups.

High Availability for Persistent Chat adds redundancy and failover capability to your persistent chat rooms. In the event of an IM and Presence Service node failure or Text Conferencing (TC) service failure, all persistent chat rooms hosted by that service are automatically hosted by the backup node or TC service. After failover, Cisco Jabber clients can seamlessly continue to use the persistent chat rooms.

External Database

The main difference between the Persistent Chat (non-HA) and Persistent Chat HA setup is around the external database requirements:

  • If Persistent Chat is deployed without HA, the external database connects to an individual chat node only. Each node that hosts persistent chat rooms requires a separate external database instance. If a chat node fails, persistent chat rooms that were hosted on that node become unavailable until the chat node comes back up.

  • If High Availability for Persistent Chat is deployed, the external database instance connects to both nodes in a subcluster (Presence Redundancy Group). If a persistent chat node fails, the backup node in the subcluster takes over, allowing chat to continue uninterrupted.

High Availability for Persistent Chat - Intercluster Example

The following illustration displays an intercluster network where Persistent Chat High Availability is deployed in Cluster 1 only. With Persistent Chat High Availability, each subcluster hosts an external database. Cluster 2 does not have Persistent Chat High Availability enabled, so there is no external database requirement. However, because the Cisco Text Conference Manager service is running on all nodes, users in Cluster 2 can join persistent chat rooms that are hosted in Cluster 1.


Note

In this example, only the chat rooms in Cluster 1 are configured to host persistent chat rooms. You can also add persistent chat support on the Cluster 2 nodes, along with external database instances. In this case, all users in either cluster would be able to join persistent chat rooms that are hosted on any node in either cluster.

Comparison of Persistent Chat (non-HA) and Persistent Chat HA Requirements

If you are deploying Persistent Chat Rooms, Cisco recommends that you deploy High Availability for Persistent Chat as well as this adds failover capability to your persistent chat rooms. However, it is not mandatory.

The following table discusses the differences between Persistent Chat deployed with and without High Availability.

Table 1. Comparison of Persistent Chat with and without High Availability

Persistent Chat (without HA)

Persistent Chat HA

Database Requirements

You require a separate external database instance for each cluster node that hosts persistent chat rooms. These external database instances can be created on the same external database server.

Recommended: For optimum performance and scalability, deploy a unique logical external database instance for each node or redundancy group an the IM and Presence cluster. However, this is not mandatory.

Minimum Requirement: You must have at least one external database instance for Persistent Chat across an IM and Presence intercluster network. However, this deployment may be inadequate for high-use networks.

Supported Database Types

  • PostgreSql (version 9.1 and above)

  • Oracle

  • Microsoft SQL Server

You require a separate external database instance for each subcluster (Presence Redundancy Group) that hosts persistent chat rooms. These external database instances can be created on the same external database server.

Recommended: For optimum performance and scalability, deploy a separate external database instance for each subcluster within an IM and Presence cluster. However, this is not mandatory.

Minimum Requirement: You require at least one external database instance for Persistent Chat HA across an IM and Presence intercluster network. However, this deployment may be inadequate for high-use networks.

Supported Database Types

  • PostgreSql (version 9.1 and above)

  • Oracle

  • Microsoft SQL Server (as of 11.5(1)SU2)

Behavior when persistent chat node fails

  • Persistent chat rooms hosted on the failed node are inaccessible until the node comes back up.

  • Users homed on the failed node fail over to the backup node in the subcluster, provided cluster redundancy is configured. However, they cannot access persistent chat rooms from the failed node.

  • Persistent chat rooms failover to the backup node in the subcluster. Users can continue messaging with no interruption of services.

  • Any users homed on the failed node also fail over.

High Availability for Persistent Chat Prerequisites

Before you configure High Availability for Persistent Chat, make sure that:

  • Persistent Chat rooms are enabled. For details, see Configure Chat Room Settings.

  • High availability is enabled in each Presence Redundancy Groups. For details, see Presence Redundancy Group Task Flow.

  • You have configured the external database. For database setup and support information, see the Database Setup Guide for the IM and Presence Service.

High Availability for Persistent Chat Task Flow

Procedure

  Command or Action Purpose

Step 1

Set up External Database

You require a separate external database instance for each subcluster where persistent chat rooms are hosted. These separate external database instances can be hosted on the same database server

Step 2

Add External Database Connection

Configure a connection to the external database from the IM and Presence Service.

Step 3

Verify High Availability for Persistent Chat Settings

Confirm your system settings for Persistent Chat High Availability.

Step 4

Start Cisco XCP Text Conference Manager Service

If the Cisco XCP Text Conference Manager service was stopped on any nodes, use this precudure to start it.

Step 5

Merge External Databases

Optional: If you are upgrading from an earlier release where you had Persistent Chat configured with multiple external databases, use this procedure to merge your external databases into a single database.

Set up External Database

To deploy High Availability for Persistent Chat, you require a separate external database instance for each subcluster where persistent chat rooms are hosted. These separate external database instances can be hosted on the same database server.

A subcluster is a redundant pair of IM and Presence nodes (Presence Redudancy Group). You can have a maximum of three subclusters in an IM and Presence cluster of 6 nodes. If HA for Persistent Chat is enabled in an IM and Presence cluster of 6 nodes, you will have three external database instances and three subcluster pairs.

You can use PostgreSQL, Oracle, or Microsoft SQL Server for the external database connection. For setup details, refer to the Database Setup Guide for IM and Presence Service.

What to do next

Add External Database Connection

Add External Database Connection

Configure connections to the High Availability for Persistent Chat external database instances from the IM and Presence Service. Make sure that both nodes in the subcluster are assigned to the same unique logical external database instance.

Procedure

Step 1

From Cisco Unified CM IM and Presence Administration, choose Messaging > External Servers Setup > External Databases.

Step 2

Click Add New.

Step 3

In the Database Name field, enter the name of external database instance.

Step 4

From the Database Type drop-down, select the type of external database that you are deploying.

Step 5

Enter the User Name and Password information for the database.

Step 6

In the Hostname field, enter the hostname or IP address of the database.

Step 7

Complete the remaining settings in the External Database Settings window. For help with the fields and their settings, refer to the online help.

Step 8

Click Save.

Step 9

Repeat this procedure to create connections to each external database instance.

What to do next

Verify High Availability for Persistent Chat Settings

Verify High Availability for Persistent Chat Settings

Use this procedure to confirm that your system is set up for High Availability for Persistent Chat.


Note

If you've already enabled High Availability for your Presence Redundancy Groups (subclusters) and your chat room configuration includes Persistent Chat then your High Availability for Persistent Chat may be completed.

Procedure

Step 1

Confirm that High Availability is enabled in each subcluster:

  1. From Cisco Unified CM Administration, choose System > Presence Redundancy Groups.

  2. Click Find and choose the Presence Redundancy Group that you want to check.

  3. Verify that the Enable High Availability check box is checked. If the check box is unchecked, then check it.

  4. Click Save.

  5. Repeat these steps for each presence redundancy group in the cluster.

Step 2

Confirm that persistent chat is enabled:

  1. From Cisco Unified CM Administration, choose Messaging > Group Chat and Persistent Chat.

  2. Confirm that the Enable Persistent Chat check box is checked. If the check box is unchecked, then check it.

  3. Click Save.

Step 3

From Cisco Unified CM Administration, confirm that the Cisco XCP Text Conference Manager Service is running on all cluster nodes.

  1. Choose System > Presence Topology.

  2. For each cluster node, click view to view the node details

  3. Under Node Status, verify that the Cisco XCP Text Conference Manager service is STARTED.

  4. In the left navigation bar, click Presence Topology to return to the cluster topology and and repeat the above steps until you've confirmed the status for all cluster nodes.

What to do next

If the Cisco XCP Text Conference Manager Service service needs to be enabled, Start Cisco XCP Text Conference Manager Service.

Start Cisco XCP Text Conference Manager Service

Use this procedure to start the Cisco XCP Text Conference Manager service. This service must be running on all cluster nodes for users on those nodes to be able to join persistent chat rooms.

Procedure

Step 1

In Cisco Unified IM and Presence Serviceability, choose Tools > Control Center - Feature Services.

Step 2

From the Server drop-down list, choose the IM and Presence cluster node and click Go.

Step 3

Under IM and Presence Services, select Cisco XCP Text Conference Manager and click Start.

Step 4

Click OK.

Step 5

(Optional) Click Refresh if you want to verify that the service has fully restarted.

Merge External Databases

Use this procedure to merge external databases.


Note

Microsoft SQL database is not supported for merging external databases.

Optional. If you have upgraded from a release prior to 11.5(1), and multiple external databases were used to manage redundancy, use the External Database Merge Tool to merge your external databases into a single database.

Example

If you have upgraded from a release prior to 11.5(1), and you had persistent chat configured with each persistent chat node connecting to a separate external database instance, use this procedure to merge the two databases in a subcluster into a single database that connects to both nodes.

Before you begin

  • Ensure that the two source destination databases are assigned correctly to each IM and Presence Service node in the presence redundancy group. This verifies that both of their schemas are valid.

  • Back up the tablespace of the destination database.

  • Ensure that there is enough space in the destination database for the new merged databases.

  • Ensure that the database users, created for the source and destination databases, have the permissions to run these commands:

    • CREATE TABLE

    • CREATE PUBLIC DATABASE LINK

  • If your database users do not have these permissions, you can use these commands to grant them:

    • PostgreSQL:

      CREATE EXTENTION—This creates the dblink and requires super user or dbowner privileges. After this, you EXECUTE privilege for dblink by running following:

      GRANT EXECUTE ON FUNCTION DBLINK_CONNECT(text) to <user>

      GRANT EXECUTE ON FUNCTION DBLINK_CONNECT(text,text) to <user>

    • Oracle:

      GRANT CREATE TABLE TO <user_name>;

      GRANT CREATE PUBLIC DATABASE LINK TO <user_name>;

  • If you are using a PostgreSQL external database, make sure that the following access is configured in the pg_hba.conf file:

    • The IM and Presence publisher node must have full access to each external database.

    • The external PostgreSQL database must have full access to each database instance. For example, if the external database is configured on 192.168.10.1 then each database instance must be configured in the pg_hba.conf file as host dbName username 192.168.10.0/24 password.

Procedure

Step 1

Log into Cisco Unified CM IM and Presence Administration on the IM and Presence Service publisher node.

Step 2

Stop the Cisco XCP Text Conference Service on the System > Services window for each IM and Presence Service node in the presence redundancy group.

Step 3

Click Messaging > External Server Setup > External Database Jobs.

Step 4

Note

 
This step is applicable for Release 15SU2 onwards.

Click on External Database Merge Job radio button.

Step 5

Click Find if you want to see the list of merge jobs. Choose Add Merge Job to add a new job.

Step 6

On the Merging External Databases window, enter the following details:

  • Choose Oracle or Postgres from the Database Type drop-down list.
  • Choose the IP address and hostname of the two source databases and the destination database that will contain the merged data.

If you chose Oracle as the Database Type enter the tablespace name and database name. If you chose Postgres as the Database Type you provide the database name.

Example

Select DB1 as external database currently in use which is mapped to the persistent chat room.

Select DB2 as destination database which is an external database on which data needs to be merged, DB2 database should not be empty and should have atleast one persistent chat room which meets the criteria MINVALUE(1).

After the merge, the data of source database DB1 and destination database DB2 will be saved in destination database DB2. Also, DB1 and DB2 will have unique data.

Step 7

In the Feature Tables pane, the Text Conference(TC) check-box is checked by default. For the current release, the other options are not available.

Step 8

Click Validate Selected Tables.

Note

 

If the Cisco XCP Text Conference service has not been stopped you receive an error message. Once the service has been stopped, validation will complete.

Step 9

If there are no errors in the Validation Details pane, click Merge Selected Tables.

Step 10

When merging has completed successfully, the Find And List External Database Jobs window is loaded. Click Find to refresh the window and view the new job.

Click Find to refresh the window and view the new job.

Click the ID of the job if you want to view its details.

Step 11

Restart the Cisco XCP Router service.

Step 12

Start the Cisco XCP Text Conference Service on both IM and Presence Service nodes.

Step 13

You must reassign the newly merged external database (destination database) to the presence redundancy group

High Availability for Persistent Chat Use Cases

The following flows demonstrate the high availability for persistent chat flows for failover and failback. This example covers an IM and Presence cluster with two nodes. An IM and Presence cluster can have a maximum of 6 nodes, which allows for three subclusters. If persistent chat rooms are hosted on all nodes, you require three separate external database instances.


Note
For this enhancement the Text Conferencing (TC) service has been made a critical service. As a result, the TC high availability failover flow remains the same even if the failover has been caused by the failure of another critical service on the node, such as the Cisco XCP Router service.
Figure 1. High Availability for Persistent Chat Structure

High Availability for Persistent Chat Failover Use Case

For this example, there are four users on four IM and Presence Service nodes with two High Availability (HA) pairs or subclusters. The users are assigned as follows:

Subcluster 1

Subcluster 2

  • Andy is on Node 1A—Node 1A hosts the chat room

  • Bob is on Node 1B

  • Catherine is on Node 2A

  • Deborah is on Node 2B

  1. All four users are chatting in the same chat room, which is hosted on Node 1A.

  2. The Text Conferencing (TC) service fails on Node 1A.

  3. After 90 seconds, the Server Recovery Manager (SRM) determines the failure of the TC critical service and starts an automatic failover.

  4. Node 1B takes over the users from 1A and transitions to the Failed Over with Critical Services not Running state, before transitioning to the HA state Running in Backup Mode.

  5. In line with the HA Failover Model, Andy is signed out from node 1A automatically and is signed in to the backup Node 1B.

  6. The other users are not affected, but continue to post messages to the chat room, which is now hosted on Node 1B.

  7. Andy enters the persistent chat room, and continues to read or post messages to the room.

High Availability Persistent Chat Fallback Use Case

For this example there are four users on four IM and Presence Service nodes with two High Availability (HA) pairs or subclusters. The users are assigned as follows:

Subcluster 1

Subcluster 2

  • Andy is on Node 1A—Node 1A hosts the chat room

  • Bob is on Node 1B

  • Catherine is on Node 2A

  • Deborah is on Node 2B

  1. All four users are chatting in the same chat room, which is hosted on Node 1A.

  2. The Text Conferencing (TC) service fails on Node 1A.

  3. Node 1B takes over the users from 1A and transitions to the Failed Over with Critical Services not Running, before transitioning to the HA state Running in Backup Mode.

  4. In line with the HA Failover model, Andy is signed out automatically and is signed in to the backup Node 1B.

  5. Bob, Catherine and Deborah are unaffected, but continue to post messages to the chat room, which is now hosted on Node 1B.

  6. The IM and Presence Service administrator starts a manual fallback.

  7. Node 1A transitions to Taking Back and Node 1B transitions to Falling Back.

  8. Andy is signed out of Node 1B. Bob, Catherine, and Deborah continue to use the persistent chat room, and once Fallback has occurred, the room is moved back to Node 1A.

  9. Node 1B moves from the HA state Falling Back to Normal and unloads its peer node rooms.

  10. Node 1A moves from the HA state Taking Back to Normal and it reloads the chat room.

  11. Andy enters the persistent chat room, and continues to read or post messages to the room.