ignite-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Sergey Antonov <antonovserge...@gmail.com>
Subject Re: {DISCUSSION] Cluster read-only mode.
Date Tue, 04 Jun 2019 11:17:20 GMT
Hello, Ivan.

>>What is a fundamental difference between them?
On inactive cluster caches aren't started. So you can't get data from
cache.

вт, 4 июн. 2019 г. в 12:16, Павлухин Иван <vololo100@gmail.com>:

> Sergey, Igniters,
>
> Sorry if my question is not very smart.
>
> I am trying to think about it from a perspective of a (newbie) user.
> And from the first glance it is not clear how a read-only cluster is
> different from a not active cluster? What is a fundamental difference
> between them? Can we combine two modes into one? If not we will need a
> clear explanation for a user.
>
> пн, 3 июн. 2019 г. в 20:15, Maxim Muzafarov <maxmuzaf@gmail.com>:
> >
> > Sergey,
> >
> > Do we have an IEP for this feature?
> >
> > What should happen when on an active cluster with put operations if we
> > receive a read-only state change request? How we guarantee that all
> > cache operations delivered (or not yet) to backups are not rejected by
> > applied read-only request? I haven't found such tests in your PR.
> >
> > I've downloaded your branch and run some tests locally. I've tried
> > DataStreamer cache loads (allowOverwrite mode false) with a concurrent
> > cluster change state request to read-only mode and I've got strange
> > behaviour. My test scenario was:
> > 1) Start DataStremer cache load;
> > 2) change cluster to read-only state;
> > 3) change state back to normal;
> >
> > When the state has been changed to `read-only` I've flooded with a lot
> > of `Failed to perform cache operation (cluster is in read-only mode)`
> > errors, but when I've reverted the state back the DataStreamer
> > continue its load without any error. I think we should not allow such
> > behaviour. We should cancel the DataStreamer task or allow it to be
> > finished.
> >
> > On Fri, 31 May 2019 at 13:00, Sergey Antonov <antonovsergey93@gmail.com>
> wrote:
> > >
> > > Hello, Zhenya, Maxim!
> > >
> > > Thank you for your replies!
> > >
> > > >> Should we also allow writes to the DistributedMetaStorage and if
> not why?
> > > Yes. DistributedMetastorage available for updates with enabled
> read-only
> > > mode. I added test about it to ClusterReadOnlyModeSelfTest
> > >
> > > >> What's the purpose for ignite-sys-cache updates still be available
?
> > > ignite-sys-cache is using in the different subcomponents, for example,
> > > security.
> > >
> > > чт, 30 мая 2019 г. в 20:30, Zhenya Stanilovsky
> <arzamas123@mail.ru.invalid>:
> > >
> > > > hi, Sergey.
> > > > What's the purpose for ignite-sys-cache updates still be available ?
> > > >
> > > > thanks !
> > > >
> > > > > Hello Igniters!
> > > > >
> > > > > I'm working on cluster read-only mode [1] feature. In this mode
> cluster
> > > > > will be available only for read operations, all data modification
> > > > > operations in user caches will be rejected
> > > > > with ClusterReadOnlyModeCheckedException. This feature could be
> helpfull
> > > > > for maintenance works (control.sh idle_verify/validate_indexes).
> > > > >
> > > > > A few points about cluster read-only mode:
> > > > > 1) Read-only mode could be enabled on active cluster only.
> > > > > 2) Read-only mode doens't store on PDS (i.e. after cluster restart
> > > > > enabled
> > > > > read-only mode will be forgotten)
> > > > > 3) Updates to ignite-sys-cache will be available with enabled
> read-only
> > > > > mode.
> > > > >
> > > > > More informartion about implementation you could find in PR [2].
> > > > >
> > > > > What do you think about this feature?
> > > > >
> > > > > [1] https://issues.apache.org/jira/browse/IGNITE-11256
> > > > > [2] https://github.com/apache/ignite/pull/6423
> > > >
> > >
> > >
> > > --
> > > BR, Sergey Antonov
>
>
>
> --
> Best regards,
> Ivan Pavlukhin
>


-- 
BR, Sergey Antonov

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message