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Reserved Cycle Alerts

· 3 min read
Byron Becker
Byron Becker
Developer

Did you know that your canister can suddenly stop saving new data if it’s on a busy subnet and you haven’t set it up to reserve enough cycles for new memory allocations?

CycleOps now has monitoring and alerting features to help you stay on top of the important but lesser-known "reserved cycles" canister configuration. Here's everything you need to know about reserved cycles, and how you can set up alerts for them in just a few minutes!

What are reserved cycles?​

Released in late 2023, the reserved cycles mechanism was designed to prevent a few canisters from easily consuming all the storage on a subnet. When a subnet is nearing capacity, canisters on that subnet must begin paying in advance for any additional storage and do so by automatically transferring some of their cycles into a dedicated “reserved cycles” pool.

Each canister can be configured to set a maximum size for its reserved cycles pool, which is known as a canister's reserved_cycles_limit configuration. All canisters have a reserved cycles limit of 5 trillion cycles (TC) by default.

What happens if I run out of reserved cycles?​

A canister which hits its reserved cycles limit will no longer be able to commit new state. This means that write endpoints will begin to fail, which can cause all sorts of production errors. You can see the types of execution errors that would occur in these instances in the official documentation:

Introducing reserved cycles monitoring and alerting​

Our new features are designed to keep these reserved cycles errors from happening. Reserved cycles monitoring insights are available for all canisters monitored via the CycleOps blackhole version >= V2, the SNS, or the NNS and allow you to easily see if any of your canisters are approaching their limit.

Check out the Reserved Cycles Alerting documentation to configure reserved cycle alerts for your canisters.

By enabling these alerts, CycleOps will make sure that you receive ample notification before this type of production error hits your canisters. Don't wait for subnet load to break your canisters, set up your alerts now! It will only take a few minutes.

Further Reading​

This original forum post remains the best place for documentation on this feature if you want to dive deeper into the details. Have questions about reserved cycles? Ask a question on this thread, or ping us on X!

Connect with us​

Find us @CycleOps on X and let us know what metrics and alerts you'd like to see us build next!