+ users@ back to the discussion. Sorry for being late to the discussion here.
When talking about "rollback" behavior, it usually involves two questions: 1) does wire protocol support rollback? 2) does data(metadata) format support rollback? For the first question, the bookkeeper provides very good wire protocol compatibility between versions. So if there are no data format changes, it is generally safe to assume that you can rollback bookies to an old version. For the second question, it depends on the changes in a given release. In certain releases, the disk format change supports rollback. In other releases, it doesn't. But you usually can still do rollback via re-replicating the data. So in general, you can assume you can do rollback.. Hope this clarifies things. - Sijie On Fri, Apr 17, 2020 at 11:48 AM Enrico Olivelli <eolive...@gmail.com> wrote: > I am forwarding this request from user@ > > We should state somehow how we support rollbacks. > > In general we do not have much support for it. > We only try to not enable new format of data on disk by default. This way > you can update the binaries and then use the new format only if you need to > use a new feature that requires such format. > If you enable the new format there is no way to rollback. > We could have some tool that tries to convert to the previous format. > > We should also talk about this topic on the website, even if we do not > still provide any tool for the rollback. > > Thoughts? > > > ---------- Forwarded message --------- > Da: Subash K <subas...@ericsson.com> > Date: Ven 17 Apr 2020, 16:32 > Subject: RE: Rollback of Apache Bookeeper > To: u...@bookkeeper.apache.org <u...@bookkeeper.apache.org> > > > Thanks a lot Enrico 😊 > > > > Regards, > > Subash Kunjupillai > > > > *From:* Enrico Olivelli <eolive...@gmail.com> > *Sent:* Friday, April 17, 2020 7:10 PM > *To:* user <u...@bookkeeper.apache.org> > *Subject:* Re: Rollback of Apache Bookeeper > > > > Subash > > I will discuss about this topic on dev@bookkeeper.apache.org list > > best regards > > Enrico > > > > Il giorno ven 17 apr 2020 alle ore 12:47 Subash K <subas...@ericsson.com> > ha scritto: > > If rollback is technically supported by Bookkeeper, may be updating the > website will help us better for now. > > > > Regards, > > Subash Kunjupillai > > > > *From:* Enrico Olivelli <eolive...@gmail.com> > *Sent:* Friday, April 17, 2020 3:44 PM > *To:* user <u...@bookkeeper.apache.org> > *Subject:* Re: Rollback of Apache Bookeeper > > > > > > Il Ven 17 Apr 2020, 11:59 Subash K <subas...@ericsson.com> ha scritto: > > Sure. But as I’m just evaluating Apache Pulsar along with Bookkeeper, we > are trying to understand various factors like Deployment, Life Cycle > Management, etc.. Because these factors will be critical as it would create > an impact on our existing product strategy. > > > > For now, we will take in that Rollback is not supported out of box. I feel > that, rollback support should be brought in at the earliest to support > organizations like us. > > In my opinion current releases of Bookkeeper support rollback. > > We do not have automated testing but we have this principle of being > backward compatible with the previous version. > > > > Maybe we just lack an official statement on the website about this rule. > > > > Enrico > > > > > > > > Regards, > > Subash Kunjupillai > > > > *From:* Enrico Olivelli <eolive...@gmail.com> > *Sent:* Friday, April 17, 2020 3:16 PM > *To:* user <u...@bookkeeper.apache.org> > *Subject:* Re: Rollback of Apache Bookeeper > > > > > > Il Ven 17 Apr 2020, 10:59 Subash K <subas...@ericsson.com> ha scritto: > > Thanks for your answers Enrico. > > > > On a high level, I understand that rollback is not supported and there is > no plan to test and support it. But technically it is possible to do a > rollback if new feature is not enabled after upgrade which is likely to > change the file format. > > > > From the document, I see that there is option to rollback the file format > after upgrade. Will this help us if we have to perform the rollback of data > format as well? > > > > bookkeeper-server/bin/bookkeeper upgrade --rollback > > Actually that command was needed for very old versions of BK. > > I have been using it since 4.4 and never needed that command. > > In my opinion it is because since 4.4 BK payed more attention in making > changes more safely > > > > A good option to you may be to check the version you are using and the one > you want to upgrade to and if you have questions ask on this ML. > > > > We will be happy to support > > > > Enrico > > > > > > > > > > Regards, > > Subash Kunjupillai > > > > *From:* Enrico Olivelli <eolive...@gmail.com> > *Sent:* 16 April 2020 19:47 > *To:* user <u...@bookkeeper.apache.org> > *Subject:* Re: Rollback of Apache Bookeeper > > > > > > > > Il giorno gio 16 apr 2020 alle ore 15:01 Subash K <subas...@ericsson.com> > ha scritto: > > Hi Enrico, > > > > Thanks for your response. > > > > I’ve following queries on top of your response: > > - In general is community planning to test and support issues in > rollback of Bookkeeper down the lane? > > Unfortunately no. > > We are only testing regular upgrades, not rollback. > > It should be doable with current docker based integration testing tools. > > > > > > > - > - We might not frequently upgrade Bookkeeper unless it is demanded by > Pulsar. In that case, we might skip few intermediate versions and > upgrade > directly to an higher version. In that case, are we foreseeing any > compatibility change that will cause hinderance during rollback? > > Usually this is not a problem. As far as you continue to upgrade from a > supported version to a supported version. If I remember correctly currently > we are officially supporting only BK 4.8 to 4.10. > > > > > - > - I’ve not fully gone through the internal working of Bookkeeper. But I > would like to understand, can old version of bookie(after rollback) > access > the new data stored by upgraded bookie? > > Usually yes, as far as you do not activate new features that need a new > format of data on disk > > > > Enrico > > > > > > > - > > > > Regards, > > Subash Kunjupillai > > > > *From:* Enrico Olivelli <eolive...@gmail.com> > *Sent:* 16 April 2020 16:05 > *To:* user <u...@bookkeeper.apache.org> > *Subject:* Re: Rollback of Apache Bookeeper > > > > Hi Subash, > > usually by default there is no problem in rolling back to the previous > version. > > For instance if you are running 4.9 and you upgrade to 4.10 your bookies > you can downgrade to 4.9 just by using the old code. > > This is because we introduce new features but they are disabled by default > at least for one release. > > > > But I suggest you to perform a test about the rollback before going to > production > > > > Enrico > > > > > > Il giorno gio 16 apr 2020 alle ore 12:23 Subash K <subas...@ericsson.com> > ha scritto: > > Hi, > > > > We are planning to introduce Apache Pulsar in our product. In general we > always support upgrade and rollback of our product. > > > So I'm trying to understand is there any defined steps provided to support > rollback of Apache Bookeeper to its earlier version after completing full > cluster upgrade? I was not able to find those information in > https://bookkeeper.apache.org/docs/latest/admin/upgrade/ > < > https://slack-redir.net/link?url=https%3A%2F%2Fbookkeeper.apache.org%2Fdocs%2Flatest%2Fadmin%2Fupgrade%2F&v=3 > > > > > > Regards, > > Subash Kunjupillai >
