a question of ISR and ack all

[XiJun Ye]

I have a question about data consistency. Kafka ISR only determines the time of 
lag, not the number of messages. Does ack=all require the replicas in the ISR 
to completely catch up with the number of messages or to meet the time 
requirement? For example, if there are 3 replicas in the ISR, 
min.insync.replicas=3 and acks=all, can the data of the 3 replicas be 
guaranteed to be completely consistent when the message is written? Instead of 
meeting the replica.lag.time.max.ms time requirement.

Re: a question of ISR and ack all

[XiJun Ye]

Thank you a lot!

> 2025年4月27日 17:48，Haruki Okada  写道：
> 
> With acks=all, it is guaranteed that a message is replicated to all ISRs on
> successful produce response.
> 
> lag.time.max is used to determine which replica is in sync, not to
> determine a message is replicated.
> 
> On Sun, Apr 27, 2025, 18:37 XiJun Ye  wrote:
> 
>> I have a question about data consistency. Kafka ISR only determines the
>> time of lag, not the number of messages. Does ack=all require the replicas
>> in the ISR to completely catch up with the number of messages or to meet
>> the time requirement? For example, if there are 3 replicas in the ISR,
>> min.insync.replicas=3 and acks=all, can the data of the 3 replicas be
>> guaranteed to be completely consistent when the message is written? Instead
>> of meeting the replica.lag.time.max.ms time requirement.
>>