I stumbled across couple of use cases where swap space was more suitable
than persistence. However, enabling both for a same region definitely
doesn't make sense to me, I would throw an exception in this case.

-Val

On Fri, Mar 2, 2018 at 9:46 AM, Denis Magda <dma...@apache.org> wrote:

> Hi Ivan,
>
>
> > Swap is legacy lightweight version of Ignite Native Persistence. In swap
> > mode, we fully rely on OS in storing offheap memory into memory-mapped
> > file. We don't provide durability guarantees in this mode. From my point
> of
> > view, after 2.1 release there's no reason to prefer swap mode over Ignite
> > Native Persistence.
> > Igniters, please correct me if there are still any actual cases.
>
>
> There is a business use case for the swap space I've come across with
> recently. Some applications want to store data entirely in RAM avoiding any
> persistence in general (Ignite persistence or 3rd party DB). It's ok for
> them to lose a data set in case of a cluster shutdown. However, they want
> to avoid OOM exception that might happen if they don't scale out the
> cluster in time. And here is the swap space comes to rescue. If a node is
> running out of RAM, the OS begins the swap-out/in the process putting off
> OOM and DevOps will have much more time to scale the cluster and rebalance
> the data.
>
> Right now we indeed can configure both Ignite Native Persistence and
> > swapping, but this makes even less sense. Node will just perform extra
> job
> > by persisting data twice.
>
>
> Guess, that's the point Prachi tried to point out. Could we throw an
> exception if a user tries to configure both? As we agreed, it's error-prone
> and doesn't make sense in general.
>
> --
> Denis
>
> On Fri, Mar 2, 2018 at 1:28 AM, Ivan Rakov <ivan.glu...@gmail.com> wrote:
>
> > Prachi,
> >
> > Swap is legacy lightweight version of Ignite Native Persistence. In swap
> > mode, we fully rely on OS in storing offheap memory into memory-mapped
> > file. We don't provide durability guarantees in this mode. From my point
> of
> > view, after 2.1 release there's no reason to prefer swap mode over Ignite
> > Native Persistence.
> > Igniters, please correct me if there are still any actual cases.
> >
> > Right now we indeed can configure both Ignite Native Persistence and
> > swapping, but this makes even less sense. Node will just perform extra
> job
> > by persisting data twice.
> >
> > Best Regards,
> > Ivan Rakov
> >
> >
> > On 02.03.2018 7:20, Prachi Garg wrote:
> >
> >> Engineers,
> >>
> >> How does persistence and swap work when both are enabled? I was under
> the
> >> impression that for a data region you can either have swap or
> persistence
> >> configured at a time, but not both. Please clarify.
> >>
> >> Thanks,
> >> -Prachi
> >>
> >>
> >
>

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