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From Dmitriy Pavlov <dpav...@apache.org>
Subject Re: {DISCUSSION] Cluster read-only mode.
Date Tue, 04 Jun 2019 11:15:24 GMT
I don't remember if we agreed on it before. But it may be so, just a
problem for me to remember it. Any big feature - it is quite a vague
definition.

My concern we'll end up with +1 inactive/uncompleted/not actual IEP. For
now, we have a number of open IEPs, and no-one resolves it. I guess it
should be part of the IEP process of 'how to' and 'when' close it. For me,
this process seems to be still incomplete.

If someone will lead all existing IEPs to be closed and finalize the
process, it would work.

вт, 4 июн. 2019 г. в 13:49, Nikolay Izhikov <nizhikov@apache.org>:

> Hello, Dmitriy.
>
> I don't agree with you.
>
> IEP should be written for any big changes in product.
> We should have it for:
>
> 1. Following contributors.
> 2. History of decision making.
> 3. Easier documenting.
>
> Without IEPs our product will become a total mess.
>
> In the Apache Kafka one can't change any public API without KIP(Kafka
> improvement proposal).
> I think it's a good practice.
>
>
> В Вт, 04/06/2019 в 13:43 +0300, Dmitriy Pavlov пишет:
> > Folks,
> >
> > Sorry for offtopic. IEP is a good tool for case design is discussed
> before
> > any implementation available. It is a good place to share the intent to
> do
> > something and provide some details. It is a better place then mile-long
> > emails.
> >
> > For now, we have code and documentation later should be updated. I don't
> > think we need to create IEP.
> >
> > Sincerely,
> > Dmitriy Pavlov
> >
> > 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
> > >
>

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