DH2i Blog Article

The Search for One HA Clustering Solution to Rule Them All: A Side-By-Side Comparison of SQL Server HA Alternatives

Josh Achtemeier
January 3, 2023

Mission-critical SQL Server workloads never sleep, and high availability (HA) clustering technology is an imperative tool in the pursuit of maximum uptime. Organizations require the ability to quickly identify single points of failure in their IT environments, and failover workloads to a host where uptime can be maintained. Not to mention, literally every second counts—as hourly revenue losses can easily approach 7-figure sums for the largest corporations.

There are numerous solutions in the IT universe that pledge to help your organization achieve high availability, but not all HA clustering is created equal. DH2i has worked with SMBs and enterprises all over the world—representing almost every industry imaginable. These organizations have broken down their selection of HA clustering solutions into three competencies that need to be heavily weighed through the technology selection process.

This article will be focusing on 4 of the most popular SQL Server HA clustering technologies out there today:

  • Windows Server Failover Clustering (WSFC) – A leading solution for Windows Server
  • Pacemaker – A leading solution for Linux
  • SIOS – A leading solution for Windows and Linux
  • DxEnterprise – DH2i’s Smart HA Clustering software for Windows, Linux, and containers

Deployment Flexibility

 It’s no secret that there are some ancient (relatively speaking) SQL Server environments out there. One of the big reasons why: traditional SQL Server clustering technology is very predisposed to complexity and lock-in due to stringent infrastructure and like-for-like requirements. Not to mention, licensing costs can really add up when you are forced to leverage Enterprise Edition SQL Server to meet your HA requirements. Some companies can get away with maintaining outdated legacy SQL Server systems for years, but for the most critical workloads, it is essential to leverage solutions that can grow organically with your SQL Server environment and not bottleneck evolution.

For our customers and other IT pros we’ve talked to, ease of adoption and deployment is a huge factor in selecting their ideal HA clustering technology. This process can be a massive undertaking, so learning how the new technology integrates with your existing environment is a big piece of the puzzle.

Below is a small chart detailing some of the critical feature differences among the four solutions being evaluated today.

Create clusters containing any mix of physical, virtual, and cloud serversNoNoYesYes
Works with Windows or LinuxNoNoYesYes
Create mixed OS clustersNoNoNoYes
Helm chart for easy deployment and support for HA SQL Server AGs in KubernetesNoNoNoYes
Require 3rd party shared or replicated storageYesYesNoYes

It’s not an all-out win for DxEnterprise relative to SIOS though. SIOS does include the convenience of having the replication piece built-in, whereas DxEnterprise requires an additional solution to facilitate shared or replicated storage. Most IT pros we’ve talked to consider this a small price to pay for the additional flexibility and enhancements that DH2i provides, but it’s an additional requirement nonetheless.

Management Experience

In a perfect world, your SQL Server HA clusters are not a blackhole of management complexity. An easy-to-administrate environment inherently contributes to the fight against downtime, because less complexity means a lower chance for human error. So, how do our four solutions stack up in several key management feature categories?

Unified management for Linux and Windows SQL ServerNoNoNoYes
Manage with GUI and CLIYesNoYesYes
Sidecar deployment for HA SQL Server AGs in KubernetesNoNoNoYes

While both SIOS and DxEnterprise can be used to provide HA for SQL Server on Windows and Linux, only DxEnterprise can truly manage the two platforms from a unified management console. This enables mixed Windows and Linux clusters, and even unlocks cross-platform failover.

A GUI and CLI are offered by most of the solutions, so that’s not a huge point of differentiation. However, DxEnterprise again pulls ahead in the realm of SQL Server containers.

A huge reservation IT teams have in pursuing stateful SQL Server containers in production is the headache of support. DH2i mitigates this with the only sidecar container technology in the industry. To further clarify, DH2i can deploy its clusterware, DxEnterprise, and SQL Server as separate, isolated container images in the same Kubernetes pod. Isolating these two entities in this way removes all custom image support headaches and makes trouble-shooting much easier with the ability to easily remove DxEnterprise from the cluster equation.

Level of Protection and High Availability Provided

Enabling an easy initial deployment and simplified ongoing management are significant factors in the selection of a SQL Server HA solution, but perhaps most important is the technical capability and security measures built-in to your SQL Server high availability solution. In other words, how does the technology in question allow your organization to achieve the nearest-to-zero downtime possible? Answering this question comes down to automation capability, failover speed, granularity of protection, and the ability to ensure total HA for today’s realistic diversity of instances, Availability Groups, and containers.

All the solutions here provide instance-level failover and unlock Always on Availability Groups. However, there are some notable differences when drilling down into security and other technical capabilities.

Automatic secure tunnels for data mirroring NoNoYes, but not automaticYes
Requires VPN for cross-site mirroringYesYesYes, optional additional protectionNo
Fully automatic failover for SQL Server AGs in KubernetesNoNoNoYes
Easily stretch clusters for disaster recoveryNoNoYesYes

DxEnterprise offers the most bang for your buck as the only “Smart” High Availability solution on our list. Smart HA is effectively the convergence of software-defined perimeter and HA technology. So, DxE enables a clustering framework that links all nodes with encrypted application-level tunnels for maximum cluster security. SIOS also offers secure tunneling technology, but the use of a virtual private network (VPN) is a notable distinction here. Leveraging VPNs runs the risk of unlocking the entirety of your environment to attack, whereas SDP application-level connections keep access much more granular and secure. Ultimately, VPN is becoming a more and more deficient technology as we transition to a cloud-based world.

In this feature breakdown, DxEnterprise also maintains its monopoly on SQL Server container capability. DxE offers the only clustering solution in the industry that unlocks automatic failover for SQL Server AGs in Kubernetes—significantly reducing overall downtime in containerized deployments. For mission-critical SQL Server, pod-level failover is simply not an option, but only DxE can mitigate this deficiency.

The Summary

The initial deployment, management experience, and overall capability of high availability clustering technology all play an important role in determining the direction your organization should go in solution adoption.

SIOS and DxEnterprise led the way in our side-by-side comparisons, and a big reason for that was the versatility of these two solutions. They remove barriers such as like-for-like requirements for infrastructure, and they also offer fully featured solutions for Windows and Linux.

So, what solution is the best? It’s still hard to answer this question with anything but, “It depends.” Not all organizations need the versatility to handle an incredibly diverse SQL Server environment, and there are plenty of instances where IT teams have no need for certain bells and whistles.

However, a completely objective statement can be made in saying DxEnterprise provides the most future-proof HA clustering solution in the industry. DxE comes out of the box with:

  • Built-in Zero Trust Network Access tunnels to connect your cluster without the vulnerabilities of VPN
  • Unified platform management and the flexibility to easily layer on top of any infrastructure
  • Full support for highly available SQL Server containers in Kubernetes

Even if it’s not on your company’s radar now, a containerized future for SQL Server appears increasingly inevitable, and DxEnterprise gives you the power to manage SQL Server containers side-by-side with your native instances on Windows and Linux.

Let us know if you’d like to see DxEnterprise in action.

If you’re interested in learning more about DH2i’s approach to smart high availability technology, get signed up for a one-on-one demo today.

The author
Josh Achtemeier

Native. Containerized. Anywhere in Between.

DH2i gets you closer to zero downtime.