EhCahce with  “diskPersistent=true” flag  is used to persist  the cache values to disk and can be used after system restarts.

If you have many caches with “diskPersistent=true” then you may get “Too many Open files Exception”.  This is because EhCache is using nearly 30 open file pointers for each cache and the default no. of open files for user in linux is 1024.  So, to avoid this exception you need to increase the No. Of. open files  per  process/user.