SQL Server High Availability

SQL Server high availability keeps your databases online when a server, a disk or a whole site fails, and shortens maintenance windows. We design the architecture that fits your recovery targets and budget, from Always On Availability Groups and failover cluster instances to log shipping and backups, and check that failover actually works, including for your applications.

When to call us

  • Your business can’t afford long outages of critical database applications.
  • Patching or maintenance needs downtime you’d rather avoid.
  • You have an Availability Group or a SQL Server failover cluster instance (FCI), but you’re not sure whether failover actually works, how long it takes, or whether your applications reconnect afterwards.
  • You need a disaster recovery site, or a recovery plan your auditors accept.
  • You are consolidating or moving to new hardware or the cloud and want availability built in.

What we design and review

Recovery targetsHow much data you can lose (RPO) and how long you can be down (RTO), per application.
Always On Availability GroupsReplicas, synchronous or asynchronous commit and readable secondaries. Contained Availability Groups also carry logins and jobs to every replica.
Distributed Availability GroupsAvailability across sites or regions, and low-downtime migrations between clusters.
Failover cluster instancesWindows Server Failover Clustering, shared storage and quorum.
Log shipping and backupsSimple, robust options where they fit, and backups that match your recovery targets.
Disaster recoveryA second site or region, multi-subnet setups and a documented failover procedure.
Application connectivityListeners, DNS aliases, MultiSubnetFailover and encrypted connections that survive a failover.
Server-level objectsLogins, jobs, linked servers and other objects that must exist on every replica.
Cloud and hybridHigh availability on virtual machines in Azure, AWS or Google Cloud, Azure SQL Managed Instance failover groups, and hybrid setups.
Monitoring and testingAlerts for replica health and lag, and regular failover tests.

How it works

  1. Requirements: we agree recovery targets per application with your business and IT teams.
  2. Review: we look at your current setup and applications.
  3. Architecture: you get a design with options, risks and costs, not a one-size-fits-all template.
  4. Implementation: we build it with your team, or guide your team through it, whichever you prefer.
  5. Failover tests: we test failover with your applications and document the procedures.

What you receive

  • An architecture matched to your recovery targets and budget.
  • Tested failover, including the applications that connect to SQL Server.
  • Runbooks for planned and unplanned failover and for recovery.

Building a database application? Our SQL Server Security & High Availability Checklist lists what an application needs to work with Availability Groups. For an example of availability built into a consolidation, see our case study.

Frequently asked questions

Availability Group or failover cluster instance?

It depends on your recovery targets, storage, edition and applications. Failover cluster instances protect the whole instance but rely on shared storage. Availability Groups protect databases without shared storage and can keep readable copies; Contained Availability Groups also include logins and jobs. We generally recommend Availability Groups, but we always choose the technology that best fits your requirements and your team’s expertise.

Do our applications need changes for high availability?

Sometimes. Applications should connect through a listener or DNS alias, not to a specific server, and should reconnect after a failover. Settings such as MultiSubnetFailover and certificate names matter too. We test this with your applications before you rely on it.

Can you review an existing Availability Group?

Yes. We check the configuration, server-level objects, monitoring, backups and application connectivity, and test failover where you allow it.

What does it cost?

It depends on your requirements and the size of your environment. You get a fixed-scope proposal before any work starts.

Need SQL Server to stay online?

Tell us which applications matter most and how long they may be down. We’ll suggest an architecture.

Discuss High AvailabilityBook a 20-Minute Call