Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups Dell servers and storage options available for AlwaysOn Availability Groups deployment.
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups This document is for informational purposes only and may contain typographical errors and technical inaccuracies. The content is provided as is, without express or implied warranties of any kind. © 2012 Dell Inc. All rights reserved. Dell and its affiliates cannot be responsible for errors or omissions in typography or photography.
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups Contents Executive summary ....................................................................................................... 4 Introduction ................................................................................................................ 4 Objectives................................................................................................................
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups Executive summary Organizations typically require that their critical applications are available to end users on a continuous basis, and thus the need for reliable solutions that provide High Availability (HA) and Disaster Recovery (DR) continues to increase. Most HA and DR solutions available today use multiple redundant components to extend these vital capabilities to hosted data.
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups discuss various server and storage options available from Del that are most conducive to optimal AVG deployments. Objectives Understanding how AlwaysOn Availability Groups may be the right choice for implementing High Availability and Disaster Recovery solutions for business critical SQL databases based on customer RTO and RPO requirements.
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups The PowerEdge R720 supports up to 7 PCIe slots and offers an interface for several available storage categories such as fiber channel, iSCSI and Direct Attached Storage (DAS), making possible the installation of applications that require high-bandwidth on the same system.
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups o Asynchronous-Commit Mode: The primary replica commits the transaction without waiting for an acknowledgement from the secondary replicas that are configured for Asynchronous-Commit mode. This mode minimizes the transaction latency, but might cause Asynchronous-Commit mode replicas to lag behind the primary replicas. This may, in turn, lead to some data loss in case of failover.
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups site. This setup can be replaced by FCI for HA and AlwaysOn Availability Groups for DR. This setup is a right choice for SMB and Enterprise customers who can invest to some extent in SAN implementations. Multi-site Implementations: Implementing Multi-site FCI across datacenters for both HA and DR. Mostly this setup uses shared storage in both the sites.
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups The Dell H710 mini-integrated PowerEdge RAID Controller (PERC) card can be used efficiently to manage internal storage of the server. The H710P mini-card is designed for enhanced performance, increased reliability, and simplified management. For more details on the H710 PERC card refer dell.com/perc.
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups Limitations: Limits on storage scalability. No enhanced SAN capabilities. AVG deployments on shared storage In addition to the failover capability provided by AlwaysOn Availability Group, we may also set up a secondary layer of availability at the server instance level. This is done by implementing SQL Server FCI together with the underlying WSFC cluster.
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups Figure 3. Scenario 1 : SQL Server FCI with AVG on shared storage In Figure 3, Node1 and Node2 are deployed in the primary site providing HA for the databases with the FCI (namely, SQL FCI1). Node3 and Node4 are implemented in the DR site. An FCI (namely, SQL FCI2) is installed on Node3 and Node4 in the DR site in order to provide High Availability at the DR site too.
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups Figure 4. Scenario 2 : SQL Server FCI with AVG on shared storage The advantage of the setup described within Figure 4 is, with the help of the read-only routing list, we may redirect or offload all read-only requests to Node3 and thereby reduce the overhead on the primary replica.
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.
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups Advantages and limitations of implementing AVG on shared storage Advantages: Cost effective HA and DR solution for Enterprise Customers Instance level protection using FCIs Support of multi-subnet FCI clustering enables a DR solution using AlwaysOn with multi-subnet FCI Flexible failover policy for granular trigger events for automatic failovers Support for variety of stora
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups In the above sample implementation, two PowerEdge R720 servers in the primary site were deployed with PCIe SSD drives. The databases that are part of the AVG are stored on the SSD drives. Remaining databases may be stored on the traditional hard drives. These two servers should be configured in synchronous commit mode with automatic failover.
Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn Availability Groups of 5-10 seconds based on a different range of tests to successfully failover to the other nodes and reestablish availability. Summary AlwaysOn Availability Groups is a new HADR feature designed to meet ever-increasing RTO and RPO requirements. It is aimed to provide more granular control to achieve HA and DR of the SQL databases.