ZooKeeper provides a very simple interface and services. ZooKeeper brings these key benefits:
Fast.ZooKeeper is especially fast with workloads where reads to the data are more common than writes. The ideal read/write ratio is about 10:1.
Reliable.ZooKeeper is replicated over a set of hosts (called an ensemble) and the servers are aware of each other. As long as a critical mass of servers is available, the ZooKeeper service will also be available. There is no single point of failure.
Simple.ZooKeeper maintain a standard hierarchical name space, similar to files and directories.
Ordered.The service maintains a record of all transactions, which can be used for higher-level abstractions, like synchronization primitives.