DISTRIBUTED KEY-VALUE STORE

摘要

Techniques are disclosed for managing a high performance, fault-tolerant, strongly consistent, distributed key-value store system. The key-value store may store information, such as metadata for a distributed file system. Fault-tolerance means that the distributed key-value store continues to provide access to values in the key-value store in spite of a certain number of node failures. To provide this capability, the key-value store may store copies of (key, value) pair on N+1 nodes in order to provide fault tolerance for the failure of up to N nodes. In addition, metadata describing which nodes store a given value is stored on 2N+1 nodes and the distributed key-value store is sized such that there are 3N+1 nodes in a cluster. Doing so allows the key, value store to tolerate a failure of N nodes, while still maintaining a consistent and available key-value store.

主权项

1. A method for accessing metadata in a distributed key-value store stored on a plurality of computing nodes, the method comprising:
receiving, by a first one of the nodes, a message from a requesting client to perform a read operation to read a value stored in the key-value store for the first key, wherein the message includes the first key and a lock sequence number and wherein the requesting client holds a lock for at least the first key; upon determining the lock sequence number is equal to or greater than a stored sequence number stored with the first key in the key value store, reading the value of the first key; and returning the key value to the requesting client.