每次都有评估产线需要多少Cassandra节点的需求,所以写几个简单的公式:
For Write:
1 | Peak WPS For Application * (Applications keyspace replicator factor / Total Cassandra Nodes Per DC) > Max WPS Capacity For Cassandra Single Node: |
For Read:
Precondition:
(1) Read Consistency level Take: LocalQuorum
(2) Every table take default configure:
1 | Peak QPS For Application * ((Applications keyspace replicator factor * 0.1 + (Applications keyspace replicator factor/ 2 + 1 )* 0.9 ) / Total Cassandra Nodes Per DC) > Max QPS Capacity For Cassandra Single Node: |
Take example:
For One Application On 7 nodes.
For Write:
1 | Peak WPS For Application * ( 3 / 7 ) < Max WPS Capacity For Cassandra Single Node: |
For Read:
1 | Peak QPS For Application * ( 2.1 / 7 ) < Max QPS Capacity For Cassandra Single Node: |
In Short
So if deployed new Casandra DC:
1 | The Cassandra node numbers > max ( 3 * Peak WPS For Application/Max WPS Capacity For Cassandra Single Node, 2.1 * Peak QPS For Application/Max QPS Capacity For Cassandra Single Node) |