Question regarding Membership Election
Hi, I read about observers in other datacenter, My question is i dont want voting across the datacenters (So i will use observers), at the same time when a DC goes down i dont want to loose the cluster, whats the solution for it? I have to have 3 nodes in primary DC to accept 1 node failure. Thats fine... but what about the other DC? how many nodes and how will i make it work? Regards, /VJ
Re: Question regarding Membership Election
Hi Vijay, Unfortunately you wont be able to keep running the observer in the other DC if the quorum in the DC 1 is dead. Most of the folks we have talked to also want to avoid voiting across colos. They usually run two instances of Zookeeper in 2 DC's and copy state of zookeeper (using a bridge) across colos to keep them in sync. Usually the data requirement across colos is very small and they are usually able to do that by copying data across with there own bridge process. Hope that helps. Thanks mahadev On 1/14/10 12:12 PM, Vijay vijay2...@gmail.com wrote: Hi, I read about observers in other datacenter, My question is i dont want voting across the datacenters (So i will use observers), at the same time when a DC goes down i dont want to loose the cluster, whats the solution for it? I have to have 3 nodes in primary DC to accept 1 node failure. Thats fine... but what about the other DC? how many nodes and how will i make it work? Regards, /VJ
Re: Question regarding Membership Election
Hi - If you put all your voting nodes in one datacenter, that datacenter becomes a 'single point of failure' for the cluster. If it gets cut off from any other datacenters, the cluster will not be available to those datacenters. If you want to withstand the failure of datacenters, then you need voting members inside every datacenter. Observers can't suddenly become voting members. You can't even put 'dormant' voting members (that never bother to vote) in your other datacenters because you would need a quorum of them to continue after the original datacenter failed. And if this was true, the original datacenter would not, by construction, contain a quorum of voting nodes. So you'd still have to vote outside the cluster. Henry 2010/1/14 Vijay vijay2...@gmail.com Hi, I read about observers in other datacenter, My question is i dont want voting across the datacenters (So i will use observers), at the same time when a DC goes down i dont want to loose the cluster, whats the solution for it? I have to have 3 nodes in primary DC to accept 1 node failure. Thats fine... but what about the other DC? how many nodes and how will i make it work? Regards, /VJ
Re: Question regarding Membership Election
Thanks Mahadev that helps, Is there any hookup's (In zoo keeper) or examples which i can take a look for the bridging process? Regards, /VJ On Thu, Jan 14, 2010 at 12:38 PM, Mahadev Konar maha...@yahoo-inc.comwrote: Hi Vijay, Unfortunately you wont be able to keep running the observer in the other DC if the quorum in the DC 1 is dead. Most of the folks we have talked to also want to avoid voiting across colos. They usually run two instances of Zookeeper in 2 DC's and copy state of zookeeper (using a bridge) across colos to keep them in sync. Usually the data requirement across colos is very small and they are usually able to do that by copying data across with there own bridge process. Hope that helps. Thanks mahadev On 1/14/10 12:12 PM, Vijay vijay2...@gmail.com wrote: Hi, I read about observers in other datacenter, My question is i dont want voting across the datacenters (So i will use observers), at the same time when a DC goes down i dont want to loose the cluster, whats the solution for it? I have to have 3 nodes in primary DC to accept 1 node failure. Thats fine... but what about the other DC? how many nodes and how will i make it work? Regards, /VJ
Re: Question regarding Membership Election
Hi Falvio, Yes i am concerned about the latency between the DC's (Across continents), We actually have 6 locations but how exactly are we going to do it if we have the 3rd DC? Regards, /VJ On Thu, Jan 14, 2010 at 1:46 PM, Flavio Junqueira f...@yahoo-inc.com wrote: Hi Vijay, I'm just curious: why exactly you want all voting nodes in a single data center? Are you concerned about latency? It might not be possible in your case, but if you have a third location available, you would be able to tolerate one location going down. -Flavio On Jan 14, 2010, at 9:12 PM, Vijay wrote: Hi, I read about observers in other datacenter, My question is i dont want voting across the datacenters (So i will use observers), at the same time when a DC goes down i dont want to loose the cluster, whats the solution for it? I have to have 3 nodes in primary DC to accept 1 node failure. Thats fine... but what about the other DC? how many nodes and how will i make it work? Regards, /VJ
