> I am worried that if only 1 node is active and online, and the other
> N-1 nodes are inactive, down, and offline, that the cluster will not
> be able to complete the operation, because not all of the data is
> available on the 1 node that is up.
Which is true, but the correct way normally is to
> The node (known as the "coordinating node" because it co-ordinates the
> request submitted by the client) will send the request to the nodes
> that are in the replica set for the row. The client need not care
> about which host it connects to, other than that it be "one of the
> ones in the corre
> I understand that CL.ONE means the read operation will block until at
> least one -replica- responds. If this node is not a replica, what
> happens?
The node (known as the "coordinating node" because it co-ordinates the
request submitted by the client) will send the request to the nodes
that are
> No. I am not entirely sure from where the confusion comes, so I will
> just try to summarize things from scratch in a brief manner.
>
> Any piece of data you store in Cassandra is going to be in a
> particular row, which has a row key.
>
> That row will have a "replica set" in the Cassandra clust
> I was/am under the impression that a node owns a particular token
> range, and does not save any data that falls outside of that range
> (with exception to any data that might be replicated to it). Based on
> what you are saying, each node owns a token range, but also maintains
> copies of data o
So my understanding of how cassandra saves data is incorrect.
I was/am under the impression that a node owns a particular token
range, and does not save any data that falls outside of that range
(with exception to any data that might be replicated to it). Based on
what you are saying, each node ow
> The goal is to configure a cluster in which reads and writes can
> complete successfully even if only 1 node is online. For this to work,
Why? You should be designing for "only 1 out of N nodes" where N is
RF. If you happen to have 3 machines now and you want 3 copies in
total that's fine. But w
Consistency and Availability are in trade-off each other.
If you use RF=7 + CL=ONE, your read/write will success if you have one
node alive during replicate data to 7 nodes.
Of course you will have a chance to read old data in this case.
If you need strong consistency, you must use CL=QUORUM.
maki
Thanks for the reply Peter.
The goal is to configure a cluster in which reads and writes can
complete successfully even if only 1 node is online. For this to work,
each node would need the entire dataset. Your example of a 3 node ring
with RF=3 would satisfy this requirement. However, if two nodes
> Read and write operations should succeed even if only 1 node is online.
>
> When a read is performed, it is performed against all active nodes.
Using QUORUM is the closest thing you get for reads without modifying
Cassandra. You can't make it wait for all nodes that happen to be up.
> When a wr
I am wondering if the following cluster figuration is possible with
cassandra, and if so, how it could be achieved. Please also feel free
to point out any issues that may make this configuration undesired
that I may not have thought of.
Suppose a cluster of N nodes.
Each node replicates the data
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