Enterprises are moving more and more applications to the cloud. The use of cloud computing is growing, and by 2016 this growth will increase to become the bulk of new IT spend, according to Gartner, Inc. 2016 will be a defining year for cloud as private cloud begins to give way to hybrid cloud, and nearly half of large enterprises will have hybrid cloud deployments by the end of 2017.
While the benefits of the cloud may be clear for applications that can tolerate brief periods of downtime, for mission-critical applications, such as SQL Server, Oracle and SAP, companies need a strategy for high availability (HA) and disaster recovery (DR) protection. While traditional SAN-based clusters are not possible in these environments, SANless clusters can provide an easy, cost-efficient alternative.
According to Gartner, IT service failover automation provides end-to-end IT service startup, shutdown and failover operations for disaster recovery (DR) and continuous availability. It establishes ordering and dependency rules as well as IT service failover policies. The potential business impact of this emerging technology is high, reducing the amount of spare infrastructure that is needed to ensure DR and continuous availability, as well as helping ensure that recovery policies work when failures occur, thus improving business process uptime.
Separating the truths and myths of HA and DR in cloud deployments can dramatically reduce data center costs and risks. In this blog, I debunk the following five myths:
Myth #1 - Clouds are HA Environments
Public cloud deployments, particularly with leading cloud providers, are high availability environments where application downtime is negligible.
The Truth - Redundancy is not the same as HA. Some cloud solutions offer some measure of data protection through redundancy. However, applications such as SQL Server and file servers still need additional configuration for automating and managing high availability and disaster recovery.
Myth #2 - Protecting business critical applications in a cloud with a cluster is impossible without shared storage
You cannot provide HA for Windows applications in a cloud using Windows Server Failover Clustering (WSFC) to create a cluster because it requires a shared storage device, such a SAN. A SAN to support WSFC is not offered in public clouds, such as Amazon EC2 and Windows Azure.
The Truth - You can provide high availability protection for Windows applications in a cloud simply by adding SANless cluster software as an ingredient and configuring a WSFC environment. The SANless software synchronizes local storage in the cloud through real-time, block level replication, providing applications with immediate access to current data in the event of a failover.
Myth #3 Remote replication isn’t needed for DR
Applications and data are protected from disaster in the cloud without additional configuration.
The Truth - Cloud providers experience downtime and regional disasters like any other large organization. While providing high availability within the cloud will protect data centers from normal hardware failures and other unexpected outages within an availability zone (Amazon) or fault domain (Azure), data centers still need to protect against regional disasters. The easiest solution is to configure a multisite (geographically separated) cluster within a cloud and extend it by adding an additional node(s) in an alternate datacenter or different geographic region.
Myth #4 - Using the cloud is “all or nothing”
The Truth - Companies can use the on-premise datacenter as its primary datacenter and cloud as the hot standby DR site. DR configurations can be assembled from a single on-premise server that includes a remote cluster member hosted in the cloud. Or, the on-premise configuration could be a traditional SAN based cluster that includes a remote cluster member hosted in a cloud. Both approaches are very cost effective alternatives to building out a separate DR site, or renting rack space in a business continuity facility.
Myth #5 - HA in a cloud has to be costly and complicated
The Truth - A cluster for high availability in a cloud can be easily created using SANless clustering software with an intuitive configuration interface that lets users create a standard WSFC in a cloud without specialized skills. SANless clustering software also eliminates the need to buy costly enterprise edition versions of Windows applications to get high availability and added disaster protection or as described in Myth 4, to eliminate the need to build out a remote recovery site.
Jerry Melnick is COO of SIOS Technology.
