Sorry to have send it twice, I mixed my email. Apology for the spam. Le lun. 20 juil. 2020 à 16:16, Michel Sumbul <michelsum...@yahoo.fr.invalid> a écrit :
> Thanks Pifta that really clear! > > If you dont mind a last question on data locality, does Ozone support > short-circuit like HDFS? > If not is it something on the roadmap? short circuit provide a significant > performance boost in HDFS world, do you think it will be the same for Ozone? > > Thanks, > Michel > Le mardi 14 juillet 2020 à 22:02:45 UTC+1, István Fajth < > fapi...@gmail.com> a écrit : > > Hi Michel, > > at the moment the placement policy is an interesting topic. > In Ozone placement is considered in terms of containers, and not blocks. > Block are sub-container structures. > The container has a lifecycle, when it is open then the pipeline attached > to it is defining the placement of data. The pipeline placement if there > are racks and we are talking about replication factor 3 pipelines then it > places two container replicas into one rack and one into an other rack. > This is a wired behaviour, and pipelines are balanced between DataNodes. If > there are no racks defined, or just one rack is defined pipeline placement > falls back to random placement that considers space available on DataNodes > and favors nodes with more available space. > > When a container gets closed, the replicas are managed by the > ReplicationManager, which has a configurable policy. There are three > policies at the moment, random, available space aware random, and rack > aware policy. > The closed containers are moved by the ReplicationManager as needed if > replication violates the policy or replicas are created or removed when > under or overreplication occurs. > > This is because Ozone aims to balance the write I/O by balancing the > pipelines. Read I/O is balanced by the random placement within the rules > defined by the policy. > > Ozone needs to harmonize the pipeline placement and the container placement > in the future as we want to add more policies for sure but at the moment > this is how placement works. > > In regards of balancing at the moment we do not have a balancing logic > built in, and we do not have a balancer tool like HDFS at the moment it is > part of the roadmap, however you can bet any balancing logic has to > consider the placement policy configured for closed containers at least. > > If you need to have a policy like the one you mentioned, the closed > container policy is pluggable, so you can write your own or even contribute > it to the project if you want. > But at the moment you need to consider the load which will be there if the > custom policy is violated by the pipeline placement then at container > closure containers have to be moved to fit with the closed container > placement policy. > > Pifta > > Michel Sumbul <michelsum...@gmail.com> ezt írta (időpont: 2020. júl. 14., > Ke 15:38): > > > Hi Pifta, > > > > Thanks for your reply. > > That's good news! Does Ozone also support other placement policies like > one > > replica in 3 different racks? That will be super useful from an > operational > > point of view. It will be possible to put in maintenance (for update or > > other task) an entire rack and be sure that 2 other replicas are in 2 > > different racks still up and running and not losing 2 replicas. > > > > Does the placement policy is also enforced during the rebalancing like in > > HDFS? > > > > Thanks, > > Michel > > > > Le jeu. 9 juil. 2020 à 13:05, István Fajth <fapi...@gmail.com> a écrit : > > > > > Hi Michel, > > > > > > yes, Ozone has topology support (currently 3 levels are supported: > root, > > > rack, node) to specify cluster topology similarly as in HDFS. With > > > replication factor 3 it works similarly as in HDFS and ensures that > > > container replicas reside in 2 racks, 2 in one rack, and 1 in another > > rack. > > > Also the FileSystem APIs (o3fs:// and ofs://) are implementing the > > methods > > > required to provide the locality information to the clients similarly > as > > in > > > HDFS, so YARN can take advantage of this information, and can bring > > compute > > > to the data as with HDFS. > > > > > > It is worth noting that there are not too many clusters currently using > > > these features, but if any issues arise we are there to react, and > there > > > are some plans as well to harden the system further. There are a couple > > of > > > items already planned after the soon to be released 0.6.0 you can check > > > into it in this JIRA (HDDS-3722) > > > <https://issues.apache.org/jira/browse/HDDS-3722>. > > > > > > If you have any questions feel free to ask further :) > > > Pifta > > > > > > Michel Sumbul <michelsum...@gmail.com> ezt írta (időpont: 2020. júl. > 9., > > > Cs, 12:57): > > > > > > > Hi guys, > > > > > > > > First thanks for your work on this project, it looks really great as > > the > > > > next evolution of HDFS (if I can say that :-) ) > > > > > > > > I saw in multiple slideshows on the web that Ozone will support data > > > > locality like HDFS. > > > > What's the status of that? Is it already implemented? > > > > > > > > Thanks, > > > > Michel > > > > > > > > > > > > > -- > > > Pifta > > > > >
