Hi Mickael, Thanks for the response.
> 4. Cordoned log directories are persisted to the metadata log via the RegisterBrokerRecord, BrokerRegistrationChangeRecord records. If a broker is offline, the controller will use the latest known state of the broker to determine the broker's cordoned log directories. I've added a sentence clarifying this point. OK, so if the broker A goes offline, and the controller is in "fenced" state, without any cordoned log dirs, then some topic created and assigned to broker A. Later, broker A starts up with all its log dirs cordoned configured. At this situation, will the broker A create the partitions? > 6. I'm leaning towards considering that scenario a configuration error. If all log directories are cordoned before the internal topics are created, then the broker will not be able to create them. This seems like a pretty strange scenario, where it's the first time you start a broker, you've cordoned all its log directory, and the internal topics (offsets and transactions) have not yet been created in the rest of the cluster. Yes, I agree that this should be a configuration error. So the follow-up question is: Suppose users encounter this issue, and how could they resolve it? Uncordon the log dir dynamically using kafka-configs.sh? Will the uncordoning config change recreate the partitions we didn't create earlier because of log dir cordoned? > The metadata log is different (not managed by LogManager), so I think it should always be created regardless if its log directory is cordoned or not. I agree we should treat "__cluster_metadata" differently. Thanks. Luke On Wed, Jul 10, 2024 at 12:42 AM Mickael Maison <mickael.mai...@gmail.com> wrote: > Hi Luke, > > 2. isCordoned() is a new method on LogDirDescription. It does not take > any arguments. It just returns true if this log directory the > LogDirDescription represents is cordoned. > > 3. Sorry that was a typo. This method will only return a log directory > that is not cordoned. Fixed > > 4. Cordoned log directories are persisted to the metadata log via the > RegisterBrokerRecord, BrokerRegistrationChangeRecord records. If a > broker is offline, the controller will use the latest known state of > the broker to determine the broker's cordoned log directories. I've > added a sentence clarifying this point. > > 5. Yes a log directory can be uncordoned. You can either update the > properties file and restart the broker or dynamically change the value > at runtime using kafka-configs. I've added a paragraph about it in the > KIP. > > 6. I'm leaning towards considering that scenario a configuration > error. If all log directories are cordoned before the internal topics > are created, then the broker will not be able to create them. This > seems like a pretty strange scenario, where it's the first time you > start a broker, you've cordoned all its log directory, and the > internal topics (offsets and transactions) have not yet been created > in the rest of the cluster. > The metadata log is different (not managed by LogManager), so I think > it should always be created regardless if its log directory is > cordoned or not. > > Thanks, > Mickael > > On Tue, Jul 9, 2024 at 3:48 PM Chia-Ping Tsai <chia7...@gmail.com> wrote: > > > > hi Mickael > > > > That is totally a good idea, but I have a question about the > implementation > > > > Do we consider making pluggable ReplicaPlacer (KIP-660) first and then > add > > another impl of ReplicaPlacer to offer cordon mechanism? Noted that > > `ReplicaPlacer` can implement Reconfigurable to get updated at runtime. > > That is similar to KIP-1066 - change cordoned.log.dirs through configs > > update. > > > > The benefit is to let users have their optimized policy for specific > > scenario. Also, it can avoid that we add more and more mechanism to our > > code base. Of course we can merge the mechanism which can be used by 99% > > users :smile > > > > Best, > > Chia-Ping > > > > > > Luke Chen <show...@gmail.com> 於 2024年7月9日 週二 下午9:07寫道： > > > > > Hi Mickael, > > > > > > Thanks for the KIP! > > > This is a long waiting feature for many users! > > > > > > Questions: > > > 1. I think piggyback the "BrokerHeartbeatRequest" to forward the > corden log > > > dir to controller makes sense to me. > > > We already did similar things for fence, controller shutdown, failed > log > > > dir...etc. > > > > > > 2. In the admin API, what parameters will the new added isCordoned() > method > > > take? > > > > > > 3. In the KIP, we said: > > > "defaultDir(): This method will not return the Uuid of a log directory > that > > > is not cordoned." > > > --> It's hard to understand. Does that mean we will only return > cordoned > > > log dir? > > > From the current java doc of the interface, it doesn't look right: > > > "Get the default directory for new partitions placed in a given > broker." > > > > > > 4. Currently, if a broker is registered and then go offline. In this > state, > > > the controller will still distribute partitions to this broker. > > > So, if now, the broker get startup with "cordoned.log.dirs" set, what > will > > > happen? > > > Will the newly assigned partitions be created successfully or not? > > > > > > 5. I think after a log dir get cordoned, we can always uncordon it, > right? > > > I think we should mention it in the KIP. > > > > > > 6. If a broker is startup with "cordoned.log.dirs" set, and does that > mean > > > the internal topics partitions (ex: __consumer_offsets) cannot be > created, > > > either? > > > Also, if this log dir is happen to be the metadata log dir, what will > > > happen to the metadata topic creation? > > > > > > Thanks. > > > Luke > > > > > > > > > On Tue, Jul 9, 2024 at 12:12 AM Mickael Maison < > mickael.mai...@gmail.com> > > > wrote: > > > > > > > Hi, > > > > > > > > Thanks for taking a look. > > > > > > > > - Yes you're right, I meant AlterPartitionReassignments. Fixed. > > > > - That's a good idea. I was expecting users to discover cordoned log > > > > directories by describing broker configurations. But being able to > > > > also get this information when describing log directories makes > sense. > > > > I've added that to the KIP. > > > > > > > > Thanks, > > > > Mickael > > > > > > > > > > > > On Fri, Jul 5, 2024 at 8:05 AM Haruki Okada <ocadar...@gmail.com> > wrote: > > > > > > > > > > Hi, > > > > > > > > > > Thank you for the KIP. > > > > > The motivation sounds make sense to me. > > > > > > > > > > I have a few questions: > > > > > > > > > > - [nits] "AlterPartitions request" in Error handling section is > > > > > "AlterPartitionReassignments request" actually, right? > > > > > - Don't we need to include cordoned information in DescribeLogDirs > > > > response > > > > > too? Some tools (e.g. CruiseControl) need to have a way to know > which > > > > > broker/log-dirs are cordoned to generate partition reassignment > > > proposal. > > > > > > > > > > Thanks, > > > > > > > > > > 2024年7月4日(木) 22:57 Mickael Maison <mickael.mai...@gmail.com>: > > > > > > > > > > > Hi, > > > > > > > > > > > > I'd like to start a discussion on KIP-1066 that introduces a > > > mechanism > > > > > > to cordon log directories and brokers. > > > > > > > > > > > > > > > > > > > > > > > > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-1066%3A+Mechanism+to+cordon+brokers+and+log+directories > > > > > > > > > > > > Thanks, > > > > > > Mickael > > > > > > > > > > > > > > > > > > > > > -- > > > > > ======================== > > > > > Okada Haruki > > > > > ocadar...@gmail.com > > > > > ======================== > > > > > > > >
