what will happen to the client connected to a crashed cassandra node

Question

In Cassandra, All nodes are equal.

we have a ring defined like (A,B,C,D)

Lets say the client has connection to Node A, because of catastrophic incident Node A is crashed, in this situation how does client can continue working ?

Answer 1

It depends on your client's driver. Usually you specify one or several "contact points" to which your client initially connects and then the driver discovers the topology of your cluster.

For example: http://www.datastax.com/drivers/java/2.0/apidocs/com/datastax/driver/core/Cluster.html

But if your driver doesn't support that, and you always specify just one node to connect, and that node is down, then...

Answer 2

If you have provided the ip address for B, C, or D at connection time, client will try to connect to the other ip addresses. (this behavior depends on what client you are working on and what the settings are). For example if you are using Java driver, it does some what load balancing and tries to communicate with A, B, C, or D given that their IP addresses are provided to the driver.