Ted, good point on the 11th location. Thanks One thing I didn't mention (clearly) is about the limitation of 'global' replication. Imaging all the 10 clusters are setup well for the 1st table:column family. Then 6 months later, the 2nd table:column enters the picture. How to limit the replication of 2nd cf to fewer clusters(let's say 3 of the 10)? least two good reasons for such use case: 1) 2nd cf is less important (or used by fewer workloads) so no need to waster network/storage to keep all 10 copies(and multiply by the # of replica within the same cluster) 2) 2nd cf is so important that legal/business requires the data to be kept within U.S, but one of the 10 cluster is in Japan.
If we simply don't create target table on 7 of the 10 clusters, the queue will growth to hit the max capacity very quickly. I am not sure about the consequence of such situation, but my guess it won't be pretty. Basically, once the business requirement evolves a bit, complexity gets larger. Demai On Fri, Nov 8, 2013 at 3:47 PM, Ted Yu <[email protected]> wrote: > bq. how about your company have a new office in the 11th locations? > > With minimum spanning tree approach, the increase in load wouldn't be > exponential. > > > On Fri, Nov 8, 2013 at 2:58 PM, Demai Ni <[email protected]> wrote: > > > Ishan, > > > > have to admit that I am a bit surprise about the need of have data center > > in 10 different locations. Well, I guess I shouldn't be, as every company > > is global now(anyone from Mars yet?) > > > > In your case, since there is only one column family. The headache is not > as > > bad. Let's call your clusters as C1, C2, ... C10 > > > > The safest way for your most critical data is still have setup the M-M > > replication by 1 to N-1. That is every cluster add the rest of clusters > as > > its peer. For example C1 will have C2, C3...C10 as its peers; C2 will > have > > C1, C3.. C10. Well, that will be a lot of data over the network. Although > > it is the best/fast way to get all the cluster sync-up. I don't like the > > idea at all(too expensive for one). > > > > Now, let's improve it a bit. C1 will setup M-M to 2 of the rest 9, and > > carefully planned the distribution so that all the clusters will get > equal > > load. Well, a system administrator has to do it manually. > > > > Now, thinking about the headache: > > 1) what if your company(that is your manager who has no idea how > difficult > > it is) decide to have one more column family to be replicated? how about > > two more? The load will grow exponentially > > 2) how about your company have a new office in the 11th locations? again, > > grow exponentially > > 3) let's say you are the best administrator, and keep nice record of > > everything (unforturnatly, Hbase alone doesn't have a good way to > maintain > > all the record of who is being replicated). And then, the admin left the > > company? or this is a global company has 10 admin at different locations. > > How do they communicate of the replication setup? > > > > :-) Well, the 3) is not too bad. I just like to point it out as it can be > > quite true for a company large enough to have 10 locations > > > > Demai > > > > > > > > > > On Fri, Nov 8, 2013 at 2:42 PM, Ishan Chhabra <[email protected] > > >wrote: > > > > > Ted: > > > Yes. It is the same table that is being written to from all locations. > A > > > single row could be updated from multiple locations, but our schema is > > > designed in a manner that writes will be independent and not clobber > each > > > other. > > > > > > > > > On Fri, Nov 8, 2013 at 2:33 PM, Ted Yu <[email protected]> wrote: > > > > > > > Ishan: > > > > In your use case, the same table is written to in 10 clusters at > > roughly > > > > the same time ? > > > > > > > > Please clarify. > > > > > > > > > > > > On Fri, Nov 8, 2013 at 2:29 PM, Ishan Chhabra < > [email protected] > > > > >wrote: > > > > > > > > > @Demai, > > > > > We actually have 10 clusters in different locations. > > > > > The replication scope is not an issue for me since I have only one > > > column > > > > > family and we want it replicated to each location. > > > > > Can you elaborate more on why a replication setup of more than 3-4 > > > > clusters > > > > > would be a headache in your opinion? > > > > > > > > > > > > > > > On Fri, Nov 8, 2013 at 2:16 PM, Ishan Chhabra < > > [email protected] > > > > > >wrote: > > > > > > > > > > > @Demai, > > > > > > Writes from B should also go to A and C. So, if I were to > continue > > on > > > > > your > > > > > > suggestion, I would setup A-B master master and B-C > master-master, > > > > which > > > > > is > > > > > > what I was proposing in the 2nd approach (MST based). > > > > > > > > > > > > @Vladimir > > > > > > That is classified. :P > > > > > > > > > > > > > > > > > > On Fri, Nov 8, 2013 at 1:20 PM, Vladimir Rodionov < > > > > > [email protected]>wrote: > > > > > > > > > > > >> *I want to setup NxN replication i.e. N clusters each > replicating > > to > > > > > each > > > > > >> other. N is expected to be around 10.* > > > > > >> > > > > > >> Preparing to thermonuclear war? > > > > > >> > > > > > >> > > > > > >> > > > > > >> > > > > > >> On Fri, Nov 8, 2013 at 1:14 PM, Ishan Chhabra < > > > > [email protected] > > > > > >> >wrote: > > > > > >> > > > > > >> > I want to setup NxN replication i.e. N clusters each > replicating > > > to > > > > > each > > > > > >> > other. N is expected to be around 10. > > > > > >> > > > > > > >> > On doing some research, I realize it is possible after > > HBASE-7709 > > > > fix, > > > > > >> but > > > > > >> > it would lead to much more data flowing in the system. eg. > > > > > >> > > > > > > >> > Lets say we have 3 clusters: A,B and C. > > > > > >> > A new write to A will go to B and then C, and also go to C > > > directly > > > > > via > > > > > >> the > > > > > >> > direct path. This leads to unnecessary network usage and > writes > > to > > > > WAL > > > > > >> of > > > > > >> > B, that should be avoided. Now imagine this with 10 clusters, > it > > > > won’t > > > > > >> > scale. > > > > > >> > > > > > > >> > One option is to create a minimum spanning tree joining all > the > > > > > clusters > > > > > >> > and make nodes replicate to their immediate peers in a > > > master-master > > > > > >> > fashion. This is much better than NxN mesh, but still has > extra > > > > > network > > > > > >> and > > > > > >> > WAL usage. It also suffers from a failure scenarios where the > a > > > > single > > > > > >> > cluster going down will pause replication to clusters > > downstream. > > > > > >> > > > > > > >> > What I really want is that the ReplicationSource should only > > > forward > > > > > >> > WALEdits with cluster-id same as the local cluster-id. This > > seems > > > > > like a > > > > > >> > straight forward patch to put in. > > > > > >> > > > > > > >> > Any thoughts on the suggested approach or alternatives? > > > > > >> > > > > > > >> > -- > > > > > >> > *Ishan Chhabra *| Rocket Scientist | RocketFuel Inc. > > > > > >> > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > *Ishan Chhabra *| Rocket Scientist | RocketFuel Inc. > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > *Ishan Chhabra *| Rocket Scientist | RocketFuel Inc. > > > > > > > > > > > > > > > > > > > > > -- > > > *Ishan Chhabra *| Rocket Scientist | RocketFuel Inc. > > > > > >
