I think, Entry log should check the exitance of directories, before going to get the last Log entries. Because, listFiles will retunr null on non existant directories or any IO Errors. We have to add the check for directory existnace check and null checks in side getLastLogID api in EntryLogger.
We may need to handle in LedgerCacheImpl also.
Do we need to add them in bad disks list? and others will refer this list before they use the dirs.