Achieving Zero Downtime for Apps in a SQL Environment


Whether unplanned or planned, downtime disrupts business continuity. The cost of downtime comes in many forms, including: 

  • Poor user experience
  • Decreased productivity
  • Wasted time and IT resources
  • Lost revenue 

With an increasing number of servers requiring ever longer maintenance windows, planned updates, such as patching software, can take hours. For software-as-aservice (SaaS) providers and businesses delivering online services, unplanned downtime brings even higher costs through broken service level agreements (SLAs) and lost revenue. In some cases, payments for SLA violations caused by system downtime can skyrocket to millions of dollars. 

For ecommerce companies, system downtime results not only in lost revenue but also in lost consumer confidence. Downtime often occurs at business peaks, coming just when companies anticipate the highest revenue – such as Black Friday or Cyber Monday – when heavier loads strain systems. At these times, every second of downtime means lost orders, as customers quickly abandon down or slow sites to shop elsewhere.

How It Works

With applications connected directly to a database server, the minute a connection is dropped, the application gets errors. ScaleArc changes that scenario by delivering an abstraction layer for the database tier that optimizes traffic flows and provides a seamless and highly reliable method to ensure availability.

Because ScaleArc is a Layer 7 routing solution and can route traffic at the SQL layer, it completely eliminates this problem and minimizes downtime through seamless and automated cross-data center failover. ScaleArc understands where a query needs to go and can determine which server it should be routed to. With a comprehensive view into the topology of servers across multiple data centers, ScaleArc can identify which is the right server for reads and which is the right server for writes.

The strategy for taking a server out of rotation during maintenance varies depending on the use case being implemented. Top use cases for planned maintenance windows include:

  • Applying software/security updates
  • Performing storage maintenance
  • Performing a backup
  • Implementing master/slave failover
  • Diagnosing potential performance issues

Each use case has its own requirements, and the strategy for taking the server out of rotation varies for each. In every instance, businesses must consider the right approach to ensure HA, while simultaneously shielding application users from errors and minimizing system downtime impact. ScaleArc lets organizations choose how gradually or abruptly they want to reduce server load by picking the right method for each kind of failover. ScaleArc offers strategies for both online and offline servers to help organizations minimize downtime depending on the particular use case.

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