Dell POWEREDGE R720XD - Manual (Page 8)

Dell High Availability and Disaster Recovery Solutions Using Microsoft SQL Server 2012 AlwaysOn
Availability Groups
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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. This method can be replaced by the
Multi-site FCI and Availability Groups for HA and DR. This setup is a right choice for large
Enterprise customers who have built a robust SAN implementation across multiple data centers.
For more information on the design patterns of AVG, refer to “ AlwaysOn Availability Design Patterns ”.
Legacy HA and DR features have their own pros and cons in terms of setup complexity, transaction
latencies, maximum number of secondary instances possible, readable secondary instances, automatic
failover/failback times, and other maintenance activities. SQL Server 2012 AVG combines the best of
legacy HA and DR features as well as providing a single feature with many enhancements in many areas
as pointed out above. Some of the benefits that AVG can offer are:
 HA and DR solutions with AlwaysOn Availability Groups (with non-shared storage)
 HA and DR solutions with FCI (with shared-storage) and multi-site cluster
 Multiple secondary replicas and hence reduced overhead on primary replicas
 Automatic routing of read-only connections to secondary replicas
 Offloading backups to the secondary replicas and prioritizing secondary replicas for backup
operations
 Automatic page repair and robust failure detection and correction when compared to
previous versions of SQL Server
 Improved flexible failover polices and diagnostics
 Flexible, integrated, easy and automated implementation with Power shell
Dell reference configuration for AVG
In the following sections, we will discuss the different AVG implementation scenarios that are possible
using Dell PowerEdge servers, incorporating internal/external storage options. We will explore the
AlwaysOn AVG deployments both on non-shared and shared storage configurations. The concepts of
AVG multi-site deployments are similar apart from the multi-site WSFC cluster setup. A detailed
description of the multi-site configuration is outside the scope of this paper.
AVG deployments on non-shared storage
In addition to SAN storage deployments, SQL Server 2012 enables us to use non-shared storage to host
databases. We can deploy AVG on local storage, or on the server’s directly attached. This feature
benefits the customer who cannot invest much on SAN deployments.
As discussed in the above sections, with its high performing internal storage and huge processing
power, Dell’s 12
th Generation PowerEdge R720xd server is an excellent single platform choice for
hosting AlwaysOn databases that have large processing power, memory, and high-performing storage
requirements. R720xd supports a maximum of 38TB of internal storage.