I have some questions on \"overflowToDisk\" attribute of element?
1) I read at this URL that :
overflowToDisk sets whether element can overflow to disk when
Elements start to overflow to the disk when you have more than maxElementsInMemory of them in the memory store. The following example creates a cache that stores 1000 elements in memory, and, if you need to store more, up to 10000 on disk:
 
For the second question, have a look at the diskPersistent parameter. If it is set to true, Ehcache will keep your data stored on the disk when you stop the JVM. The following example demonstrates this: