High Availability (HA) is a hosting plan that offers a second EC2 web server, which effectively shortens the time it takes to get your website back on its feet should some serious infrastructure failure happen, like a simple failed hard drive, or a natural disaster. All Pagely HA configurations use two different Availability Zones (effectively, data centers) to host your site — to hopefully prevent most natural disaster scenarios.
Our standard non-HA plans provide a single dedicated instance with a separate highly-available shared cluster RDS database for supporting your WordPress site. For many business cases, this is more than reliable enough, but for certain business cases, downtime of any significant length cannot be tolerated.
The Pagely Disaster Recovery document (pdf) lays out in detail what an HA setup can do for your business. In practical terms, if your non-HA server goes down from, say, a hard drive failure, it could take anywhere from 1 to 4 hours to get your website functioning again, depending on the type of failure, the size of your website, etc. But if you had an HA setup, this timeframe would be reduced significantly — to just 1 to 5 minutes. That is a level of security and reliability that is sometimes justified based on the core function of your website, and how demanding your customers — internal and external — are.
Active/Active HA vs. Active/Passive HA
Active/Active
Active/Active HA means you have two active nodes — two web servers serving HTML/WordPress traffic to web browser clients at the same time. This is the highest-end HA solution, and is suitable for the most demanding use cases. Due to the nature of this setup, it can handle more peak load traffic than an Active/Passive setup.
Active/Passive
Active/Passive HA means you have only one web server at a time — the ‘Active’ or ‘Primary’ server — serving HTML/WordPress traffic to web browser clients. The second server, the ‘Passive’ or ‘Secondary’ server, is a warm standby — it is synced to the Active server and just sits idly by as a backup server and waits for the Active server to fail — which hopefully it never does. But if and when the Active server fails, the Passive server kicks into gear and starts serving traffic. Meanwhile, Pagely gets the main, previously-Active server, back up and running — and when it is running again, we re-point the traffic to it, the Primary server.
There are other technical and operational considerations when choosing between Active/Active and Active/Passive configurations, but the two main considerations are:
- Cost effectiveness / Budget (Active/Passive is more affordable)
- Peak load (Higher peak load available in an Active/Active setup)
Read our blog article: Scaling Up Vs. Scaling Out – What’s the Difference? to best understand when each is best suited towards specific goals and needs.
Choosing High Availability For Your Website
High Availability is beneficial for software-specific problems, as well as better management of traffic surges. HA affords you the luxury of having multiple points of failure automatically set in motion to secure more stability, and protection, from downtime for your WordPress sites. With each AWS EC2 instance, located in a separate Availability Zone within an AWS region, customers can be reassured of higher resiliency and measures in place for advanced uptime standards.
As with most things associated with information technology, in certain circumstances server software can unexpectedly become unresponsive (while rare under Amazon’s stellar track record), which can then allow the secondary server to assume full responsibility and pick up the slack. HA is designed to minimize that risk one step further.
24/7 Ongoing Monitoring
Our response time to restore availability is extremely prompt, with active 24/7 monitoring for all plan options at Pagely, and HA CNAME health checks in place for immediate alerting to our DevOps experts.
If you have any questions about determining which solution is ideal for your organization’s web requirements, chat with our sales staff who are happy to offer you consultative advice.