Is this from the 1.1 line, perhaps? In my experience it could be very flappy 
for no particular reason we could discover. 1.1 is a pretty dusty version. 
Upgrading into the 2.1 or later would be a good idea. If you have to upgrade in 
place without down time, you will need to go through many upgrades to get to 
the latest versions. (The late versions of 1.2 are pretty stable, though.)

Also, you can look at the phi_convict_threshold Cassandra.yaml parameter to 
help with network flakiness. Default is 8, I believe in most versions. 
Increasing to 10 or 12 might help.

Finally, a 2 node cluster doesn't give you many of the benefits of a 
distributed system. Consider adding some nodes, if you can.

Sean Durity - Lead Cassandra Admin
Big DATA Team
For support, create a 
JIRA<https://portal.homedepot.com/sites/bigdata/Shared%20Documents/Jira%20Hadoop%20Support%20Workflow.pdf>

From: Michael Fong [mailto:michael.f...@ruckuswireless.com]
Sent: Wednesday, March 23, 2016 4:12 AM
To: user@cassandra.apache.org
Subject: Gossip heartbeat and packet capture

Hi, all,


We are trying to reason the possible scenarios when a C*(v1.x) cluster 
connection keeps flapping in production. (Two node cluster, each node keeps 
marking the other node DOWN but came back UP within seconds; multiple times a 
day) We have checked the load on the cluster i- very light and low GC 
activities also. We have also checked the network interface / devices were 
working just fine on the nodes during the incidence. We are changing our 
investigation direction to the network topology/settings, so we are thinking to 
capture gossip heartbeat packet to verify if the packet is received as expected 
on the other end.

Has anyone tried to capture the packet of gossip internode communication? What 
would be the filter / criteria to grep heartbeat-related packet only?

Thanks in advance!


Michael

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