Hi Dong! Thanks for the feedback!
You bring up a good point in that the AtMinIsr metric cannot be used to identify failure in the mentioned scenarios. I admit the motivation section placed too much emphasis on "identifying failure". I have modified the KIP to reflect the implementation as the AtMinIsr metric is intended to serve as a warning as one more failure to a partition AtMinIsr will cause producers with acks=ALL configured to fail. It has an additional benefit when minIsr=1 as it will warn us that the entire partition is at risk of going offline, but that is more of a side effect that only applies in that scenario (minIsr=1). Regards, Kevin On Tue, Feb 26, 2019 at 5:11 PM Dong Lin <lindon...@gmail.com> wrote: > Hey Kevin, > > Thanks for the proposal! > > It seems that the proposed implementation does not match the motivation. > The motivation suggests that the operator wants to tell the planned > maintenance (e.g. broker restart) from unplanned failure (e.g. network > failure). But the use of the metric AtMinIsr does not really differentiate > between these causes of the reduced number of ISR. For example, an > unplanned failure can cause ISR to drop from 3 to 2 but it can still be > higher than the minIsr (say 1). And a planned maintenance can cause ISR to > drop from 3 to 2, which trigger the AtMinIsr metric if minIsr=2. Can you > update the design doc to fix or explain this issue? > > Thanks, > Dong > > On Tue, Feb 12, 2019 at 9:02 AM Kevin Lu <lu.ke...@berkeley.edu> wrote: > > > Hi All, > > > > Getting the discussion thread started for KIP-427 in case anyone is free > > right now. > > > > I’d like to propose a new category of topic partitions *AtMinIsr* which > are > > partitions that only have the minimum number of in sync replicas left in > > the ISR set (as configured by min.insync.replicas). > > > > This would add two new metrics *ReplicaManager.AtMinIsrPartitionCount *& > > *Partition.AtMinIsr*, and a new TopicCommand option* > > --at-min-isr-partitions* to help in monitoring and alerting. > > > > KIP link: KIP-427: Add AtMinIsr topic partition category (new metric & > > TopicCommand option) > > < > > > https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=103089398 > > > > > > > Please take a look and let me know what you think. > > > > Regards, > > Kevin > > >
