By High-availability environments are only as reliable as their last tested failover. Most organizations skip that test because the cost of taking a production system offline feels too high, and then pay far more when an untested backup server fails to come online during an actual outage. The gap between a configured HA system and a validated one is where $300,000-per-hour downtime events happen.
In this interview on TFiR, Cassius Rhue, Vice President, Customer Experience at SIOS Technology, walks through the organizational and technical strategies for testing HA environments in ways that build real confidence without unnecessary production exposure.
Guest: Cassius Rhue, Vice President, Customer Experience at SIOS Technology
Show: TFiR
Here is what every platform engineer and IT operations team responsible for high-availability systems needs to know.
Technical Deep Dive
Q: What is the biggest challenge organizations face when testing HA environments in production?
Cassius Rhue, Vice President, Customer Experience at SIOS Technology, identifies the primary challenge as securing stakeholder agreement for the maintenance window required to conduct that testing. In environments where one hour of downtime can cost $300,000 or more, business stakeholders are highly resistant to approving any planned offline period. The burden falls on the engineers responsible for maintaining those systems to build a compelling business case before they can validate that failover will actually work.
“The biggest challenge I have seen organizations face when trying to test HA environments in production is securing agreement from the business stakeholders for the maintenance window required for that testing.” — Cassius Rhue, Vice President, Customer Experience, SIOS Technology
Q: How do you justify HA testing downtime to business stakeholders who resist maintenance windows?
Rhue advises framing proactive testing as a cost-controlled, scheduled event versus an uncontrolled, extended outage. A planned maintenance window carries a known, fixed cost at a time chosen for minimal business impact. An unplanned outage extended by hours because a backup server is misconfigured, client applications are hardcoded to a specific address, or data has not been synced properly carries a far higher and unpredictable cost. Articulating that comparison directly to stakeholders is the mechanism for getting sign-off.
“Taking a proactive measure might cost one fixed amount at a particular time in the year where it’s least critical to the business. But having a downtime extended by hours because you discovered the backup server is not configured properly, you want to avoid that.” — Cassius Rhue, Vice President, Customer Experience, SIOS Technology
Q: What specific failure scenarios make untested HA environments dangerous?
Rhue identifies three concrete failure modes that only surface during an actual failover event when testing has been skipped: backup servers that are not properly configured, version mismatches between application instances, and client applications that are hardcoded to a specific IP or hostname and cannot reconnect to the failover node. Data synchronization gaps between primary and secondary nodes are a fourth. Each of these turns a recoverable event into an extended, chaotic outage.
“You’re scrambling to figure out what happened, why the backup server is not properly configured, or why there’s an error between application versions, or why some particular client application is unable to reconnect.” — Cassius Rhue, Vice President, Customer Experience, SIOS Technology
Q: How do you build a like-for-like QA environment for HA testing?
Rhue recommends establishing a QA environment that replicates the services, databases, and applications that are configured for high availability in production. That environment must include test clients and sufficient mock data, along with the same supporting software stack. The goal is to validate architecture decisions and Runbook procedures before they are ever needed in production, which reduces both the frequency and scope of testing required in the live environment.
“Establishing a QA environment that has the same services, databases or applications that are going to be made highly available, making sure you have test clients and that you have sufficient mock data and other supporting software in this QA environment lets you validate a lot of your architecture.” — Cassius Rhue, Vice President, Customer Experience, SIOS Technology
Q: Does a validated QA environment eliminate the need for production HA testing?
No. Rhue is explicit that a like-for-like QA environment reduces the risk and frequency of production testing but does not replace it. QA validation builds confidence in architecture and Runbook procedures, which lowers the amount of production testing needed on a regular basis. Production failover testing remains a requirement because the live environment carries variables that a QA replica cannot fully reproduce.
“That reduces the risk and the hesitancy of testing in production, but it does not eliminate it. You still need to test in your production environment. It just reduces how much testing you would have to do on a frequent basis.” — Cassius Rhue, Vice President, Customer Experience, SIOS Technology
Resources & Documentation
- SIOS Technology, high-availability clustering and disaster recovery software for critical applications
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👇 Click to Read Full Raw Transcript
Swapnil Bhartiya: Can you talk about what are the biggest challenges organizations face when testing HA environments in production? And how can they reduce risk while still building confidence in their system?
Cassius Rhue: Yeah. So one of the biggest challenges, I’d say the biggest challenge I have seen organizations face when trying to test HA environments in production is securing agreement from the business stakeholders for the maintenance window required for that testing. That’s also, you know, getting business justification and building a story for the key stakeholders to sign off. We’re talking about systems where even one hour of downtime could be as expensive as $300,000. These stakeholders are very hesitant to have those systems offline. And so the challenge becomes, for those who are responsible for maintaining those systems, who are responsible for guaranteeing that the system will be available in a crisis, that failover will work, is making those stakeholders aware that doing this proactive testing, while it may cost some time for the system be offline or in maintenance mode, it also adds some resource costs that you can explain to them the savings that happen when you’re not in chaos mode, when you’re not scrambling to figure out what happened, why the backup server is not properly configured, or why there’s an error between application versions, or why some particular client application is unable to reconnect. So articulating the value will help you overcome that challenge. For businesses that are really hesitant to take a maintenance window for that, the other way to so reducing that risk or hesitancy is just articulating the value of doing testing in advance. Right. Making them aware that taking a proactive measure might cost one fixed amount at a particular time in the year where it’s least critical to the business. But having a downtime extended by hours because you discovered the backup servers not configured properly, clients are hard coded to a particular address or data hasn’t been synced properly, you want to avoid that and just explain to the business that in the long run, doing that testing reduces the cost and risk of chaos. Another way that I advise our our customers to reduce the risk and reduce that kind of hesitancy about using HA production systems for all of your testing, is to make a like for like copy of your production environment. Right? So that’s establishing a QA environment that has the same services, databases or applications that are going to be made highly available, making sure you have test clients and that you have sufficient mock data and other supporting software in this QA environment. And then you can go through a lot of your tests and have the confidence that things are going to work because you validated a lot of your architecture. You validated a lot of your procedures in Runbook, and. And that does reduce the risk. Now, I want to say that reduces the risk and the hesitancy of testing and production, but it does not eliminate it. You still need to test in your production environment. It just reduces how much testing you would have to do on a frequent basis.
