Dell PowerEdge R720xd Dell High Availability and Disaster Recovery Solutions U - Page 13
Creating AVG with FCI, FCI with AVG deployment setting,
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Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups We validated the configuration outlined in Figure 4 using four PowerEdge R720 servers. Figure 5 shows the replica configuration window of the New Availability Group wizard. Figure 5. Creating AVG with FCI In Figure 5, MYFCI is name of the FCI (running on either Node1 or Node2) and is configured as the primary replica with Synchronous-Commit mode. Node3 is configured as secondary replica with Synchronous-Commit mode in the primary site. Node4 is configured as another secondary replica with Asynchronous-Commit mode at the DR site. The readable secondary option has been set to "ReadIntent Only" for all the nodes. The Automatic Failover option has been disabled for MYFCI instance as automatic failover is not supported when FCIs is implemented with AVG. Another important setting to be considered is NodeWeight. In order to avoid the impact of failures in the DR site, we may set the "NodeWeight" parameter of Node4 to zero so that Node4 will not participate in cluster quorum voting. When we set the "NodeWeight" of Node4 to 0, we may have to change the quorum configuration to "Node Majority". In this case only first three nodes (on the primary site) will take part in quorum voting. But this configuration can sustain only 1 node failure. More configuration details of this setup are shown in Figure 6. Figure 6. FCI with AVG deployment setting As shown in Figure 6, there will not be any data loss as long as the AVG databases are failover/failback among the Node1, 2 and 3. There may be a data loss, however, when AVG databases are failover to Node4 in DR site as Node4 is configured as Asynchronous-Commit mode. 13