Created JIRA ticket for this issue - https://issues.apache.org/jira/browse/IGNITE-7902
On Fri, Mar 2, 2018 at 10:34 AM, Valentin Kulichenko < [email protected]> wrote: > 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 <[email protected]> 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 <[email protected]> > 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 > > >> > > >> > > > > > >
