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From Todd Palino <tpal...@linkedin.com>
Subject Re: question about mirror maker
Date Mon, 12 May 2014 03:48:23 GMT
Yes, on both counts. Putting the mirror maker in the same datacenter in
the target cluster is exactly what we do as well. We also monitor both the
consumer lag (by comparing the offsets stored in Zookeeper and the tail
offset on the brokers), and the number of dropped and failed messages on
the mirror maker producer side. The other thing to do is to make sure to
check very carefully when you are changing anything about the producer
configuration, to assure that you have not made a mistake.


On 5/11/14, 9:12 AM, "Weide Zhang" <weoccc@gmail.com> wrote:

>Hi Todd,
>Thanks for your answer. with regard to fail over for mirror maker, does
>that mean if i have 4 mirror maker running in different machines with same
>consumer group, it will auto load balance if one of the mirror maker fails
>? Also, it looks to prevent mirror maker commit wrong (consumer work but
>not producer) due to cross data center network issue, mirror maker need to
>be placed along with the target cluster so that this scenario is minimized
>On Sat, May 10, 2014 at 11:39 PM, Todd Palino <tpalino@linkedin.com>
>> Well, if you have a cluster in each datacenter, all with the same
>> you can¹t just mirror the messages between them, as you will create a
>> loop. The way we do it is to have a ³local² cluster and an ³aggregate²
>> cluster. The local cluster has the data for only that datacenter. Then
>> run mirror makers that copy the messages from each of the local clusters
>> into the aggregate cluster. Everything produces into the local clusters,
>> and nothing produces into the aggregate clusters. In general, consumers
>> consume from the aggregate cluster (unless they specifically want only
>> local data).
>> The mirror maker is as fault tolerant as any other consumer. That is,
>>if a
>> mirror maker goes down, the others configured with the same consumer
>> (we generally run at least 4 for any mirror maker, sometimes up to 10)
>> will rebalance and start back up from the last committed offset. What
>> need to watch out for is if the mirror maker is unable to produce
>> messages, for example, if the network goes down. If it can still consume
>> messages, but cannot produce them, you will lose messages as the
>> will continue to commit offsets with no knowledge that the producer is
>> failing.
>> -Todd
>> On 5/8/14, 11:20 AM, "Weide Zhang" <weoccc@gmail.com> wrote:
>> >Hi,
>> >
>> >I have a question about mirror maker. say I have 3 data centers each
>> >producing topic 'A' with separate kafka cluster running. if 3 of the
>> >need to be kept in sync with each other, shall i create 3 mirror maker
>> >each data center to get the data from the other two ?
>> >
>> >also, it mentioned that mirror making is not fault tolerant ? so what
>> >be the behavior of mirror consumer if it went down due to network and
>> >up ? do they catch up with last offset from which they last mirror ? If
>> >so,
>> >is it enabled by default or I have to configure  ?
>> >
>> >Thanks a lot,
>> >
>> >Weide

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