MySQL Cluster FAQ----MySQL master-slave configuration and cluster differences, how many computers in the cluster? such as

The extract part is shown here, as below,

What's the difference in using Cluster
vs using replication?

In a replication system, one MySQL master server updates one or more slave servers. The transactions are committed sequentially, so a slow transaction can cause the server to lag behind the primary server for a period of time. This also means that if the primary server fails, Then from the server may be missing the last small portion of the transaction log. If you are using a transactional secure storage engine, for example InnoDB , then the transaction log will be fully logged to the server or not at all. However, replication does not guarantee consistency between the primary and the data on the server. In a MySQL cluster, all data is always synchronized, and transactions committed on any data node are synchronized to all other data nodes. If one data node fails, other normal data nodes can still maintain data consistency .

In a replication setup, a master MySQL server updates one or
More slaves. Transactions is committed sequentially, and a
Slow transaction can cause the slave to lag behind the
Master. This means if the master fails, it is possible
That the slave might not having recorded the last few
Transactions. If a transaction-safe engine such as
InnoDBis being used, a transaction would
Either be complete on the slave or not applied at all, but
Replication does not guarantee, all data on the master
And the slave is consistent at all times. In MySQL
Cluster, all data nodes is kept in synchrony, and a
Transaction committed by any one data node was committed for
All data nodes. In the event of a data node failure, all
Remaining data nodes remain in a consistent state.

In short, whereas standard MySQL replication is
Asynchronous, MySQL Cluster is synchronous.

We have implemented (asynchronous) replication for Cluster
In MySQL 5.1. This includes the capability to replicate both
Between-clusters, and from a-MySQL cluster to a
Non-cluster MySQL Server. However, we don't plan to
Backport This functionality to MySQL 5.0.

How Many computers does I need to run a cluster, and why?

The cluster requires a minimum of 3 computers. But we 建议 'd better be 4. There are 2 units that run the Management node and the SQL node, and 2 as the data node. The purpose of taking 2 data nodes is to improve the redundancy of the data. The management node is placed on a separate host to ensure that the quorum service is provided in the event of a failure of a data node.

A minimum of three computers is required to run a viable
Cluster. However, the minimum
recommended Number of
Computers in a MySQL Cluster are four:one each to run the
Management and SQL nodes, and computers to serve as data
Nodes. The purpose of the data nodes is to provide
redundancy; The management node must run on a separate
Guarantee continued arbitration services in the
Event that one of the data nodes fails.

To provide increased throughput and high availability, you
Should use multiple SQL nodes (MySQL Servers connected to
The cluster). It is also possible (although not strictly
necessary) to run multiple management servers.

Reference: a.10. MySQL 5.0 faq-Cluster

a.10 MySQL 5.6 Faq:mysql Cluster

MySQL Cluster FAQ----MySQL master-slave configuration and cluster differences, how many computers in the cluster? such as