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From Brian Nixon <brian.nixon...@gmail.com>
Subject Re: ZooKeeper 3.4 to 3.5.x upgrade: "No snapshot found, but there are log entries. Something is broken!"
Date Thu, 21 Jun 2018 23:31:06 GMT
We're discussing some potential approaches to getting smooth upgrades from
3.4 to 3.5 on the issue ZOOKEEPER-3056 (thanks, Michael, for creating it).
A few ideas have been proposed so far and I'm happy to see more
perspectives represented there.

As one way of unblocking those who need an upgrade while we're discussing,
I've also uploaded an empty snapshot file to the issue and attached a
procedure that will allow you to upgrade to 3.5 by respecting the
constraints created by ZOOKEEPER-2325.

On Tue, Jun 5, 2018 at 2:31 PM, Sijie Guo <sijie@apache.org> wrote:

> Do you think it is worth reverting that change first? Or maybe put the
> validation in a if-else branch and controlled by a configuration setting.
> So people who is using 3.4.6 can turn the flag off for upgrading and turn
> the flag on after upgrade.
>
> On 2018/06/05 14:32:42, Michael Han <hanm@apache.org> wrote:
> > A simple workaround is to make sure we always have at least one snapshot
> > file before upgrading (e.g. we can use a small snapCount to force snap
> > generation). Though from user perspective this is not ideal, but at least
> > this would unblock the upgrade.
> >
> > I'll create a JIRA so we can discuss what's the best to address this
> issue.
> >
> > On Mon, Jun 4, 2018 at 11:32 PM, Matteo Merli <mmerli@apache.org> wrote:
> >
> > > That is correct, there are only a few transaction so the snapshot has
> not
> > > been triggered yet.
> > >
> > > The question is more on how to plan for seamless upgrade, from 3.4.10
> to
> > > 3.5.x, from an end users perspective.
> > >
> > > On Mon, Jun 4, 2018 at 11:15 PM Michael Han <hanm@apache.org> wrote:
> > >
> > >> Hi Matteo,
> > >>
> > >> Maybe your ZK instance did not take a snapshot at all - it's possible
> if
> > >> your total number of transactions less than the configured snapCount
> > >> (default value is 10000) at the time you are doing upgrade. You could
> check
> > >> your transaction log file and the snapCount configuration see if this
> is
> > >> the case or not.
> > >>
> > >>
> > >> On Mon, Jun 4, 2018 at 10:02 PM, Matteo Merli <mmerli@apache.org>
> wrote:
> > >>
> > >>>
> > >>> >> Also can you advice the steps for people who using 3.4.x to
> upgrade
> > >>>> to 3.5.4-beta
> > >>>>
> > >>>> The only catch I remember is that if you are using a version older
> than
> > >>>> 3.4.6, you'd need to upgrade through 3.4.6 first before upgrading
> to 3.5.x,
> > >>>> if you are doing a rolling upgrade and want to keep the liveness
of
> the
> > >>>> quorum. See more https://zookeeper.apache.org/doc/r3.5.3-beta/
> > >>>> zookeeperReconfig.html#ch_reconfig_upgrade.
> > >>>>
> > >>>
> > >>>
> > >>> Hi Michael,
> > >>>
> > >>> This is happening upgrading from 3.4.10 to 3.5.4. It's single node
> > >>> embedded ZK server, part of a self-contained standalone service.
> > >>>
> > >>> Definitely , in 3.4.10 single mode, the snapshot dosesn't get
> created on
> > >>> bootstrap.
> > >>>
> > >>> Thanks,
> > >>> Matteo
> > >>> --
> > >>> Matteo Merli
> > >>> <mmerli@apache.org>
> > >>>
> > >>
> > >> --
> > > Matteo Merli
> > > <mmerli@apache.org>
> > >
> >
>

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