Highly Available systems are those that are designed to withstand failure of system components. Depending on the nature of the business, any unplanned outage may be catastrophic, making the selection and implementation of an appropriate High Availability strategy crucial.

Not to be confused with Disaster Recovery (what to do when failure occurs), High Availability is concerned with avoiding downtime. Often measured by the amount of 9's, presented here is a graph displaying the amount of downtime permitted at various levels of High Availability targets;

 

 

Other than hardware-level redundancy such as RAID storage and UPS, there are several High Availability features baked into SQL Server, and the use of each depends on budget, the edition & version of SQL Server, and the Recovery Point and Recovery Time objectives.

StrataDB has deep and real-world implementation experience with the following High Availability features;

✔	Failover Clustering
✔	Database Mirroring
✔	Transaction Log Shipping
✔	Replication

 

In addition to the above features, the next version of SQL Server (codenamed Denali) due out in the next 12 months will be introducing a new High Availability feature called AlwaysOn.

Customers often ask us for our opinion on which High Availability feature is best for them. In response, we've developed a High Availability Assessment package, which includes;

✔	Assessment of the current SQL Server environment and its susceptibility to a range of possible disaster events
✔	Assessment of the recovery time objective (acceptable lead time to restore service)
✔	Assessment of the recovery point objective (how much data loss is acceptable)
✔	Selection of an appropriate High Availability technique which aligns with both the recovery time and point objectives, and one which takes into account budget constraints and the current version/edition of SQL Server being used
✔	Documentation of the proposed High Availability architecture

 

Contact us today for a no-obligations discussion on our High Availability capabilities and how they can assist your business in minimising unplanned downtime.