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From Mohit Anchlia <>
Subject Re: Multi datacenter, WAN hiccups and replication
Date Tue, 26 Jun 2012 15:00:48 GMT
On Tue, Jun 26, 2012 at 7:52 AM, Karthik N <> wrote:

> My Cassandra ring spans two DCs. I use local quorum with replication
> factor=3. I do a write in DC1 with local quorum. Data gets written to
> multiple nodes in DC1. For the same write to propagate to DC2 only one
> copy is sent from the coordinator node in DC1 to a coordinator node in
> DC2 for optimizing traffic over the WAN (from what I have read in the
> Cassandra documentation)
> Will a Wan hiccup result in a Hinted Handoff (HH) being created in
> DC1's coordinator for DC2 to be delivered when the Wan link is up
> again?

I have seen hinted handoff messages in the log files when the remote DC is
unreachable. But this mechanism is only used for a the time defined in
cassandra.yaml file.

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