Hi Ketan, You are correct that observers need connection to quorum as well. There have been quite a few discussions on multi colo replication and read only mode of ZooKeeper.
Here are the jiras for those: https://issues.apache.org/jira/browse/ZOOKEEPER-784 and https://issues.apache.org/jira/browse/ZOOKEEPER-892 These have been mostly targeted at exactly a use case like yours. Please take a look and them and feel free to contribute/comment on the jiras. -- thanks mahadev @mahadevkonar On Tue, May 3, 2011 at 2:07 PM, Ketan Gangatirkar <[email protected]> wrote: > Hi. We're considering ZooKeeper for coordinating operations across > multiple data centers. These data centers will occasionally be > disconnected. We were planning on using observers in remote data > centers. Our applications can survive being unable to *write* to > ZooKeeper, but they do need to be able to read from it, even if the > data were stale. > > On further examination, it looks like observers must always be > connected to the quorum to function at all. Is this correct? Does > anyone have suggestions for how to work around this problem? The > first thing that comes to mind is duplicating the required data in > some other local data store and falling back on that when the DC > becomes disconnected. I imagine the disadvantages of that are obvious > to everyone. I hope someone can share some great idea that allows me > to avoid that miserable fate. Thanks. > > -- > Ketan Gangatirkar > [email protected] >
