Final answer:
By default, 30% of peer nodes are typically restarted at a time during a rolling restart, but this value can vary and is configurable in the system settings.
Step-by-step explanation:
The question refers to the process of performing a rolling restart in a distributed system that uses peer nodes. By default, in many distributed systems, 30% of peer nodes are restarted at a time during a rolling restart. This is often considered a safe default as it helps avoid overloading remaining peers while still allowing the system to continue operating. However, this is not a universal default and depends on the specific technology or platform being used.
The configuration for the percentage of peer nodes to restart can typically be adjusted in the system's configuration files or management console. It allows administrators to balance the speed of the restart process against the redundancy and performance of the overall system during updates or maintenance. Instructions for changing this setting are usually found in the distributed system's documentation.