OK, let me find the original HBCK2 issue and see how can we make progress
on it.

BTW, on scan performance, Zheng Hu has done a work to get about 40%
performance back in this issue for 100% scan case on ycsb

https://issues.apache.org/jira/browse/HBASE-21657

Andrew Purtell <apurt...@apache.org> 于2019年1月19日周六 上午8:14写道:

> Lars was testing tip of branch-2 with Phoenix and said scans were 50%
> slower than branch-1. I’ll try and get him to provide more details. Anyway
> after hbck2 is complete issues like that will come out in the testing we’d
> do as part of sanity checking a move of the pointer.
>
> On Fri, Jan 18, 2019 at 4:02 PM Zach York <zyork.contribut...@gmail.com>
> wrote:
>
> > I agree with the sentiment around HBCK2. I think these kind of recovery
> > tools are essential before marking something stable.
> >
> > I also remember when we did testing around HBase 2.x/2.1 that we were
> > getting perf degradations and couldn't seem to get performance to be as
> > good as we were getting in the 1.x line.
> >
> > - Zach
> >
> > On Thu, Jan 17, 2019 at 11:06 PM Pankaj kr <pankaj...@huawei.com> wrote:
> >
> > > Yeah, HBCK2/ OfflineMetaRepair tools are really required to migrate old
> > > version data to HBase-2. We have use cases where we are using these
> tools
> > > to rebuild the meta for further region assignment.
> > > Similar discussion is going on HBASE-21665, after fixing the NPE and
> > > rebuilding the meta, master don't assign the regions as we skip the
> empty
> > > regions while loading meta during master startup.
> > >
> > > A big +1 from my side on this...
> > >
> > > Regards,
> > > Pankaj
> > >
> > > -----Original Message-----
> > > From: 张铎(Duo Zhang) [mailto:palomino...@gmail.com]
> > > Sent: 18 January 2019 11:55
> > > To: HBase Dev List <dev@hbase.apache.org>
> > > Subject: Re: [DISCUSS] Moving towards a branch-2 line that can get the
> > > 'stable' pointer.
> > >
> > > So the first priority is to make progress on HBCK2? If we all agree,
> > let's
> > > start to work.
> > >
> > > Andrew Purtell <apurt...@apache.org> 于2019年1月18日周五 下午12:31写道:
> > >
> > > > Sorry, let me add... Check all the boxes on that list and I'm +1 for
> > > > moving the stable pointer (modulo some time to pound on the candidate
> > > > to really put it through its paces, like two weeks of chaos...)
> > > >
> > > > On Thu, Jan 17, 2019 at 8:28 PM Andrew Purtell <apurt...@apache.org>
> > > > wrote:
> > > >
> > > > > I do not believe we should move the stable pointer to any 2.x until
> > > > > HBCK2 is feature complete. We can discuss what that milestone
> should
> > > look like.
> > > > > At a minimum, I think we need:
> > > > >
> > > > >    - Rebuild meta from region metadata in the filesystem, aka
> offline
> > > > >    meta rebuild.
> > > > >    - Fix assignment errors (undeployed regions, double assignments
> > > (yes,
> > > > >    should not be possible), etc)
> > > > >    - Fix region holes, overlaps, and other errors in the region
> chain
> > > > >    - Fix failed split and merge transactions that have failed to
> roll
> > > > >    back due to some bug (related to previous)
> > > > >    - Enumerate store files to determine file level corruption and
> > > > >    sideline corrupt files
> > > > >    - Fix hfile link problems (dangling / broken)
> > > > >
> > > > > This is a list of the real problems I have had to fix in production
> > > > > at least once (in the past 10 years...).
> > > > >
> > > > > On Thu, Jan 17, 2019 at 8:19 PM 张铎(Duo Zhang)
> > > > > <palomino...@gmail.com>
> > > > > wrote:
> > > > >
> > > > >> There are still lots of small new features which we want to
> > > > >> integrate
> > > > into
> > > > >> branch-2 so I'm -1 on making release directly from branch-2.
> > > > >> Backporting at once before release is a pain I'd say, I've tried
> > > > >> this many times recently, as we have to follow up the community
> > > > >> version...Let's make a branch-2.2 when we want to release 2.2.0,
> > > > >> and maybe also retire the branch-2.0?
> > > > >>
> > > > >> For the stable pointer, I think 2.1.x maybe a good candidate?
> > > > >> Though we know that we may still have some bugs for the AMv2, but
> > > > >> actually we all know that the AMv1 for all the branch-1.x also has
> > > > >> lots of bugs, that's why hbck is very important.
> > > > >>
> > > > >> And also +! on making progress on HBCK2, we need to port he useful
> > > > >> features of HBCK1 to HBCK2. There is no software can guarantee
> that
> > > > >> there is no bug, so FWIW we should have a way to fix broken
> > > > >> clusters.
> > > > >>
> > > > >> Sean Busbey <bus...@apache.org> 于2019年1月18日周五 上午11:47写道:
> > > > >>
> > > > >> > There are a few related topics I'd like to discuss and I figured
> > > > >> > this subject line is the most likely to get a bit of attention.
> > > > >> > :)
> > > > >> >
> > > > >> > First, I'd like us all to get on the same page wrt the current
> > > > >> > state of branch-2. Personally, I don't think it can be released
> > > > >> > as-is with a 2.y version because folks can't rolling upgrade
> from
> > > > >> > 2.0 or 2.1 to it due to the current implementation of
> > > > >> > HBASE-20881. As Duo has mentioned a couple of times, folks have
> > > > >> > to ensure there are no region transitions around during the
> > > > >> > upgrade. I think that will be prohibitive for folks looking to
> > > upgrade. What do other folks think?
> > > > >> >
> > > > >> > Second, I think our recent discussions around the need for
> > > > >> > shifting to more minor releases for HBase 1.y also applies to
> the
> > > 2.y branches.
> > > > >> > branch-2 hasn't had a release since 2.1.0 came out in July 2018.
> > > > >> > That's a scary long amount of time. I think it contributes to us
> > > > >> > ending up with changes like the above since it's easy to think
> > > > >> > about the branch as something that has a lot of time before the
> > > > >> > next release.
> > > > >> >
> > > > >> > Personally, I'd like to see us skip making minor-release
> specific
> > > > >> > branches for a bit unless a CVE fix or something comes up.
> > > > >> > Ideally, that would mean we work towards a 2.2.0 release
> directly
> > > > >> > from branch-2 and then 2.2.1, etc. When we have a feature that's
> > > > >> > ready to backport from the master branch for a release we then
> > > > >> > update branch-2's version to be 2.3.0.
> > > > >> >
> > > > >> > Or maybe we try set a regular cadence to feature releases by
> > > > >> > having
> > > > >> > branch-2 release a new minor, two months of new maintenance
> > > > >> > releases, followed by a new minor. That would mean after the
> last
> > > > >> > of the maintenance releases we'd have a window of a few weeks
> > > > >> > where we can all decide which features in master are mature
> > > > >> > enough to backport for the new minor release.
> > > > >> >
> > > > >> > Lastly, what would it take for folks to feel confident moving
> the
> > > > >> > 'stable' pointer to a HBase 2.y? Is there a major gap still on
> > > > >> > assignment stability? Is it a more thorough look at performance?
> > > > >> > More time to ensure HBCK2 has good coverage of failure modes
> that
> > > need it?
> > > > >> >
> > > > >>
> > > > >
> > > > >
> > > > > --
> > > > > Best regards,
> > > > > Andrew
> > > > >
> > > > > Words like orphans lost among the crosstalk, meaning torn from
> > > > > truth's decrepit hands
> > > > >    - A23, Crosstalk
> > > > >
> > > >
> > > >
> > > > --
> > > > Best regards,
> > > > Andrew
> > > >
> > > > Words like orphans lost among the crosstalk, meaning torn from
> truth's
> > > > decrepit hands
> > > >    - A23, Crosstalk
> > > >
> > >
> >
> --
> Best regards,
> Andrew
>
> Words like orphans lost among the crosstalk, meaning torn from truth's
> decrepit hands
>    - A23, Crosstalk
>

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