Adding Database Servers to a Cluster

This article describes the procedure for adding one or more database servers as part of the ScaleArc cluster setup process. If you are adding database servers to an already existing cluster, refer to this article on Adding a server.
When more than one database is added to a cluster, ScaleArc is able to seamlessly load balance SQL traffic across the multiple databases. Database load balancing is one of the key benefits of deploying ScaleArc.
Database servers can be added during the cluster creation steps as described below. ScaleArc also supports the management of database servers (Add, Modify, Delete) later after the cluster has already been set up.

If adding more than one server, you must ensure these servers are already configured as a singular cluster. Configure the cluster outbound LAN connection IP address to connect to the database servers.

Additionally, if you are planning to use windows authentication, configure the Network LAN Manager authentication level to 'Use NTLMv2 response only' on each database server.

Database Server Configuration Options

ScaleArc supports a number of common database replication topologies.

Use the following options to add database servers to your cluster. Make a choice based on the replication technology in use between:

  1. Adding Standalone or Transaction Replication servers
  2. Adding Amazon Aurora Instances

Adding Standalone or Transaction Replication Servers

Follow the steps below to add and configure standalone or transaction replication database server(s) to your cluster:

  1. Execute the cluster creation steps described in Creating Clusters.
  2. Complete setting up the network and database access.

  3. Locate the Servers panel on the Create Cluster screen. This is the fourth panel on the screen.
    CreateCluster_Servers.png

  4. Select Server from the Server Type drop-down menu.

    CreateCluster_Servers2.png

  5. Enter the IP address/FQDN (Fully Qualified Domain Name) of the database server you wish to add.
  6. Enter the port number. 
  7. Select the server role from the drop-down list (see table below).

    • Server_roles.png 

      Option Description
      Read + Write

      Setting for primary Servers. This setting tells ScaleArc that this server can take write operations.

      Read

      Setting for secondary or backup Servers that can take read-only transactions at runtime.

      Standby + Read

      Setting for secondary machines that can take Read or Write transactions but ScaleArc only delivers Read queries to this server type. In the event of the Read+Write server becoming unavailable ScaleArc, automatically promotes servers with this type to be a Read+Write server and demotes the original server to Read+Standby.

      Standby, No Traffic

      Warm standby server for ScaleArc. This server cannot or should not take transactions at runtime unless the Read+Write Server becomes unavailable, at which time ScaleArc demotes the Read+Write server and promotes the Standby Server to be Read+Write. Often used for other replication types such as log shipping.

  8. Click Add Server to load the server information. Repeat steps 5-8 to add more database servers as required. 

  9. If you wish to clone (copy) the configurations of a specific cluster, including the database servers added to that cluster, select the cluster of choice from the drop-down in the ScaleArc Cluster Settings section. 
    Clone_cluster_configuration.png

    • The Start Cluster After Setup setting determines if the cluster is ON or OFF immediately following a setup. Select the checkbox as appropriate.
  10. Click on Setup Cluster to complete the configuration. 
  11. If you have incorrectly configured the settings, you may see an error alert.
  12. Click OK. Review the details in the log and address the error in the appropriate section of the screen.
    SA-Demo-CreateClus-CreateClusErrLog-8-5.png
     
  13. Click Finish to set up the cluster.
  14. When completed, the system posts a notification screen. 
    Create_cluster_success.png

  15. The cluster appears in the CONTROL PANEL section of the dashboard along with the database servers that were added. The Cluster ID appears below the cluster name.
    Cluster_MySQL.png
     
  16. If you had selected the checkbox to Start Cluster After Setup (this is selected by default), the newly created cluster's green icon indicates that the cluster is already running. If you had unchecked this option, the cluster icon will be red, indicating that you need to start the cluster. Click START in the Status column to run the cluster. The icon should turn green indicating it is now running. You can stop the cluster using the STOP button. 

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Adding Amazon Aurora Instances

Prerequisites
  • Before you begin, complete setting up the network (make sure DNS and Search Domain are set up correctly).

    Recommended configuration for the AWS Load Balancer while working with ScaleArc

    The complete duration for Aurora failover process takes about one minute. During this time, ScaleArc holds client connections in a surge queue while waiting for the new master to become available. By default, the AWS Load Balancer has an idle timeout of 60 seconds. If it is used in front of ScaleArc and if there is an Aurora failover, then the load balancer may terminate application connections after 60 seconds of idle time. To avoid this scenario, it is recommended that you set the "idle-timeout" attribute of the AWS Load Balancer to 120 seconds.

Add an Amazon Aurora database instance to a ScaleArc cluster by following these steps:

  1. Execute the cluster creation steps described in Creating Clusters.

  2. Complete setting up the network and database access.

  3. Locate the Servers panel on the Create Cluster screen. This is the fourth panel on the screen.
  4. Select Cluster for Server Type and Aurora from the dropdown.
    AuroraCluster.png

  5. Click Configure Server
  6. Specify the Aurora node's information. 
  7. Enter the Access Key, Access ID, Region, and name of the Aurora cluster.
    AddAuroraNodeInfo.png

  8. Click on Fetch Aurora Nodes. This will connect to Amazon RDS and fetch all the configured servers.
    FetchAuroraNodes.png


  9. Click on Add Servers to add all the servers to the Aurora cluster.  
  10. The Start Cluster After Setup setting determines if the cluster is ON or OFF immediately following the setup.
  11. Click Setup Cluster to complete the configuration. 
  12. If you have incorrectly configured the settings, you may see an error alert.
  13. Click OK. Any error appears in the Configuration log section of the screen. Review the details and address the error to complete the setup. Note that you can also download the detailed error message.
    Aurora_configuration_log.png
     
  14. Click Finish to set up the cluster.
  15. When completed, a popup dialog confirms the cluster was successfully created. 
    Create_cluster_success.png

  16. The newly created cluster appears in the CONTROL PANEL section of the dashboard along with the Aurora database instances that were added.
    AuroraClusterLandingPage.png

  17. If you had selected the checkbox to Start Cluster After Setup (this is selected by default), the newly created cluster's green icon indicates that the cluster is already running. If you had unchecked this option, the cluster icon will be red, indicating that you need to start the cluster. Click START in the Status column to run the cluster. The icon should turn green indicating it is now running. You can stop the cluster using the STOP button.

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