Github user kanzhang commented on the pull request:
https://github.com/apache/spark/pull/1082#issuecomment-50279342
@JoshRosen one use case I could imagine is a user creates a series of RDDs
along the way (e.g., in a shell) and she later wants to find out which RDDs are
persisted and perhaps unpersist some of them, but she didn't keep all RDD
references in one convenient place (e.g., a collection) to look through using
```getStorageLevel()```.
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