Hi, all data is stored in a distributed file system or object store (HDFS, S3, Ceph, ...) and ZooKeeper only stores pointers to that data.
Cheers, Fabian 2018-02-15 11:08 GMT+01:00 Krzysztof Białek <krzysiek.bia...@gmail.com>: > Alright, just came across the first real-life problem with my Consul HA > implementation. > In Consul KV store there is a limit of 512kB per node and JobGraph of one > of my apps exceeded it. > In ZK there seems to be similar zNode Limit = 1MB > How did you workaround it? Or maybe I serialize the JobGraph wrong? > > On Thu, Feb 15, 2018 at 8:47 AM, Krzysztof Białek < > krzysiek.bia...@gmail.com> wrote: > >> I have very little experience with ZK and cannot explain the differences >> between ZK and Consul by myself. However there are some comparisions >> available: >> * https://www.consul.io/intro/vs/zookeeper.html - done by Consul so may >> be biased >> * https://www.slideshare.net/IvanGlushkov/zookeeper-vs-consul-41882991 >> * https://jakon.me/2017/01/consul-deployment-orchestration/ >> >> Regarding testing - I did basic failover scenarios on my workstation with >> 2 JobManagers, 2 TaskManagers and WindowJoin example app with checkpointing >> and restarting turned on. >> I was running the cluster no longer than for few hours. >> >> For now I'd like to open Flink for alternative HA backends ( >> https://issues.apache.org/jira/browse/FLINK-8660) >> >> >> On Wed, Feb 14, 2018 at 1:47 PM, Chesnay Schepler <ches...@apache.org> >> wrote: >> >>> Hello, >>> >>> I don't know anything about Consul but the prospect of having other >>> options beside Zookeeper is very interesting. It's rather surprising how >>> little you had to modify existing classes to get this to work. >>> >>> It may take a bit until someone provides proper feedback as the >>> community is currently prepping 2 releases (1.4.1 and 1.5), please don't be >>> discouraged by this. >>> >>> I saw that your branch was based on the 1.4 version. In 1.5 we reworked >>> the distributed architecture of Flink (in an initiative commonly referred >>> to as FLIP-6) which may affect your work. >>> >>> 2 things to note from my side: >>> It would also be helpful if you could explain the differences between ZK >>> and Consul and how they stack up in terms of guarantees etc. . >>> How did you test your solution so far? (Like how long was a cluster >>> running, what failure scenarios) >>> >>> >>> On 13.02.2018 21:38, Krzysztof Białek wrote: >>> >>> I'd like to get your opinion about this idea. I found related JIRA issue >>> FLINK-2366, but it seems to be dead. To attract your attention I copy >>> my comment here. >>> >>> As an experiment I've implemented Flink HA on top of Consul. The >>> implementation is working fine in the "lab" but is not battle tested yet. >>> The source code is available at https://github.com/kbialek/ >>> flink/tree/feature/consul (flink-runtime package >>> org.apache.flink.runtime.consul) >>> >>> Why?. Generally I'd like to keep as less moving parts as possible. We do >>> not have Zookeeper running, but Consul is already in place. And in the end >>> freedom of choice is a good thing. >>> >>> It would be great to see built-in Consul support in Flink someday, but >>> if it is not expected then I suggest a little refactoring to open >>> possibility to configure HighAvailabilityServicesFactory. As far as I >>> can see this should be enough to inject any HA implementation. >>> >>> Regards, >>> Krzysztof >>> >>> >>> >> >
