Thanks for your quickly response, and also excellent job on this project.

For such kind of HA, we need do 2 way data sync. After failover to DC2, the data change will be replicate to DC1 again, we had done same work with our cross DC file system HA solution, so I prefer to this solution at beginning. :)

Thanks for your suggestion, I think you are right, you guys do very good job on the replication & failover with Cassandra, it was one of the best part of this project. So let me try it. Thanks again.


Regards
-Santal



2009/10/14 Jonathan Ellis <jbellis@gmail.com>
On Wed, Oct 14, 2009 at 1:53 AM, Santal Li <santal.li@gmail.com> wrote:
> There was another way for cross data center HA,  how about add some kind of
> action hook, which can catch all the Cassandra.Iface function call(insert ,
> batch_insert , remove ...) , then send the call to another Cassandra cluster
> in remote data center? If so, there will be 1 Cassandra clusters in each 2
> data centers, and have a extra application replicate data between the two
> cluster. I prefer with this solution, because it looks more simple and
> uncoupled 2 data center, BTW, from the source code, it looks was not very
> hard to add a hook for this purpose , how do you think about it? is there
> anyone meet the same requirements,  can you please give me some suggestion.

That works fine, until you actually have a failure.  Then how do you
re-sync your clusters after you've done some writes in the second DC?
The advantage to letting Cassandra handle replication + failover is
all the hard parts are done already. :)

-Jonathan