체크 포인트 기능 요약

2.1 Checkpoint Service

The Checkpoint Service provides a facility for processes to record checkpoint dataincrementally, which can be used to protect an application against failures. 

When recovering from fail-over or switch-over situations, the checkpoint data can be retrieved, and execution can be resumed from the state recorded before the failure.

Checkpoints are cluster-wide entities that are designated by unique names. 

A copy of the data stored in a checkpoint is called a checkpoint replica; for performance reasons,a checkpoint replica is typically stored in main memory rather than on disk. A checkpoint may have several checkpoint replicas stored on different nodes1 in the cluster to protect it against node failures.

To avoid accumulation of unused checkpoints in the system, checkpoint replicas

have a retention time. 

When a checkpoint has not been opened by any process for the duration of the retention time, the Checkpoint Service automatically deletes the checkpoint.