7.5.2 Specifying the data multiplicity
Use the eads.replication.factor parameter to specify the multiplicity of data.
The number of EADS servers that make up a cluster must be at least the data multiplicity ![[Figure]](GRAPHICS/ZUENG005.GIF)
2 - 1. Data consistency is maintained as long as the number of EADS servers that have shut down due to failures is less than
the number of data copies plus the original. Therefore, as the multiplicity becomes higher, reliability and fault tolerance
improve.
On the other hand, more memory might be required and communication overhead between EADS servers might increase.
You must take into account advantages and disadvantages such as these when you set the multiplicity.
The following example sets 3 as the multiplicity.
|
|
![[Figure]](GRAPHICS/ZU070520.GIF)
If the multiplicity is set to 3, at least five EADS servers are required. If there are five EADS servers and two of them shut down due to failures, no data loss occurs.
For details about how redundant copies of data are created, see 2.8 Creating redundant copies of data.