[Solved] Consider a Kafka topic with 3 replicas and ISR = [replica1, re... If replica3 is removed from ISR due to lag, what will happen when a producer sends a message with acks=all and min.insync.replicas=2? | Kafka

Kafka - Cluster Architecture

Consider a Kafka topic with 3 replicas and ISR = [replica1, replica2, replica3]. If replica3 is removed from ISR due to lag, what will happen when a producer sends a message with acks=all and min.insync.replicas=2?

AThe producer will retry indefinitely until replica3 rejoins ISR

BThe message will be rejected because ISR size is less than min.insync.replicas

CThe message will be written but only to the leader, ignoring ISR

DThe message will be successfully written as long as replica1 and replica2 acknowledge

Step-by-Step Solution

Solution:

Step 1: Understand ISR and min.insync.replicas
Producer with acks=all requires acknowledgments from at least min.insync.replicas in ISR.
Step 2: Check ISR size after removal
ISR now has 2 replicas (replica1, replica2), which meets min.insync.replicas=2.
Step 3: Determine outcome
Message will be accepted as required acknowledgments are met.
Final Answer:
The message will be successfully written as long as replica1 and replica2 acknowledge -> Option D
Quick Check:
ISR count >= min.insync.replicas allows write [OK]

Quick Trick: Writes succeed if ISR count ≥ min.insync.replicas [OK]

Common Mistakes:

Assuming message rejected if any replica leaves ISR
Confusing acks=all with requiring all replicas
Thinking producer retries indefinitely

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More Kafka Quizzes

If replica3 is removed from ISR due to lag, what will happen when a producer sends a message with acks=all and min.insync.replicas=2?

Step 1: Understand ISR and min.insync.replicas

Step 2: Check ISR size after removal

Step 3: Determine outcome

Final Answer:

Quick Check:

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