Hi, What I meant fromActive/standby model is that even though data is being replicated (asynchronously) to standby DC , client will only access the data from active DC (let's say using local_quorum).
you have "to switch" your clients without any issues since your writes are replicated on all DC. --> that is not true because there is a chance of mutation drop. (Hints, read repair may help to some extent but data consistency is not guaranteed unless you run anti- entropy repair ) On Thu, Jan 16, 2020, 3:45 PM Ahmed Eljami <ahmed.elj...@gmail.com> wrote: > Hello, > > What do you mean by active/standby model ? Cassandra is designed to be > active/active inter DC. > So you have "to switch" your clients without any issues since your writes > are replicated on all DC. > > Unless you would mean by active/standby that the keyspace is not > replicated on the second DC ? > > Le jeu. 16 janv. 2020 à 09:35, Laxmikant Upadhyay <laxmikant....@gmail.com> > a écrit : > >> We have 2 dc in active/standby model. At any given point if we want to >> switch to standby dc, how will we make sure that data is consistent with >> active site? Note that repair runs at its scheduled time. >> >> >> I am thinking of below approaches : >> >> 1.Before switching run the repair (although it assure consistency mostly >> but repair itself may take long time to complete) >> >> 2. Monitor the dropped message bean : If no message dropped since last >> successful repair then it is good to switch without running repair. >> >> 3. Monitor the hints backlog (files in hint directory), if no backlog >> then it is good to switch without running repair. >> >> >> >> I am interested to know how other people are solving this issue and make >> fast switch-over assuring consistency. >> >> -- >> >> regards, >> Laxmikant Upadhyay >> >> > > -- > Cordialement; > > Ahmed ELJAMI >
