MongoDB Documentation  Release 3.0.4 MongoDB Enterprise Features Auditing Additional Information Changes Affecting Compatibility Storage Engine Change Storage Engine to WiredTiger sections in Upgrade MongoDB to 3.0 (page 810) See also: Data Files Must Correspond to Configured Storage Engine The files in the dbPath directory must correspond to the configured storage engine (i.e. --storageEngine ). mongod will not start if dbPath contains data files created by a storage engine other than the one specified by --storageEngine . WiredTiger and Driver Version Compatibility For MongoDB 3.0 deployments that use the WiredTiger storage engine  the following operations return no output when issued in previous versions of the mongo shell or drivers: Use the 3.0 mongo shell or the 3.0 compatible version (page 808) of the official drivers when connecting to 3.0 mongod instances that use WiredTiger. The 2.6.8 mongo shell is also compatible with 3.0 mongod instances that use WiredTiger. Chapter 12. Release Notes 804 • db.getCollectionNames() • db.collection.getIndexes() • show collections • show tables Auditing (page 330) in MongoDB Enterprise can filter on any field in the audit message (page 424)  including the fields returned in the param (page 425) document. This enhancement  along with the auditAuthorizationSuccess parameter  enables auditing to filter on CRUD operations. However  enabling auditAuthorizationSuccess to audit of all authorization successes degrades performance more than auditing only the authorization failures. Compatibility Changes in MongoDB 3.0 The following 3.0 changes can affect the compatibility with older ver- sions of MongoDB. See Release Notes for MongoDB 3.0 (page 785) for the full list of the 3.0 changes. Configuration File Options Changes With the introduction of additional storage engines in 3.0  some configuration file options have changed: 3.0 mongod instances are backward compatible with existing configuration files  but will issue warnings when if you attempt to use the old settings. Previous Setting New Setting storage.journal.commitIntervalMs storage.mmapv1.journal.commitIntervalMs storage.journal.debugFlags storage.mmapv1.journal.debugFlags storage.nsSize storage.mmapv1.nsSize storage.preallocDataFiles storage.mmapv1.preallocDataFiles storage.quota.enforced storage.mmapv1.quota.enforced storage.quota.maxFilesPerDB storage.mmapv1.quota.maxFilesPerDB storage.smallFiles storage.mmapv1.smallFiles