As far as I know Cassandra doesn't use internal queueing mechanism specific to replication. Cassandra sends the write the remote DC and after that it's upto the tcp/ip stack to deal with buffering. If requests starts to timeout Cassandra would use HH upto certain time. For longer outage you would have to run repair.
Also look at tcp/ip tuning parameters that are helpful with your scenario: http://kaivanov.blogspot.com/2010/09/linux-tcp-tuning.html Run iperf and test the latency. On Wed, Sep 5, 2012 at 8:22 PM, Venkat Rama <venkata.s.r...@gmail.com>wrote: > Hi, > > We have multi DC Cassandra ring with 2 DCs setup. We use LOCAL_QUORUM > for writes and reads. The network we have seen between the DC is sometimes > flaky lasting few minutes to few 10 of minutes. > > I wanted to know what is the best way to measure/monitor either the lag or > replication latency between the data centers. Are there any metrics I can > monitor to find the backlog of data that needs to be transferred? > > Thanks in advance. > > VR >
