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Low reliability and high availability?

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#1

Since availability depends on reliability, please show a case when we have low reliability and high availability? I think low reliability always leads to low availability.

#2

Hi @Pengyu_Zhang !!
Yes, reliability and availability are closely related, and generally, low reliability is associated with low availability. However, there can be specific scenarios where high availability is maintained despite low reliability through redundancy and fault tolerance mechanisms. One classic example is the use of mirrored or redundant systems.

Consider a scenario where you have two identical servers, A and B, and they both serve the same application. Each server individually has low reliability because they frequently encounter faults and failures. However, you’ve set up these servers in a mirrored configuration. This means that they are exact copies of each other, and the system can switch between them seamlessly if one server fails. This configuration is often used in critical systems to ensure high availability despite low individual server reliability.

Here’s how it works:

  1. Low Reliability Servers (A and B): Each server, A and B, has a low individual reliability, meaning they are prone to failures.

  2. Redundancy: The system is designed in such a way that if server A fails, the system automatically switches to server B.

  3. High Availability: Even though the individual servers have low reliability, the overall system maintains high availability. If one server fails, the other takes over immediately, minimizing downtime and ensuring the system remains available to users.

This is just one example of how you can achieve high availability despite low reliability through redundancy and fault tolerance mechanisms. However, it’s essential to note that this approach requires additional resources and complexity to maintain the redundancy, which may not be practical or cost-effective in all situations. In many cases, improving reliability is still the primary goal to achieve high availability more efficiently.
I hope it helps. Happy Learning :blush: