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 > >> > >> > > >
