MongoDB Documentation, Release 3.0.4 See also: Enhanced Sharding and Replication Administration Configuration Options YAML File Format Operational Changes Storage Networking See Storage (page 89) for more information about MongoDB’s storage system. To use the previous exact-fit allocation strategy : usePowerOf2Sizes is now the default allocation strategy for all new collections. The new allocation strategy uses more storage relative to total document size but results in lower levels of storage fragmentation and more predictable storage capacity planning over time. MongoDB 2.6 supports a YAML-based configuration file format in addition to the previous configuration file format. See the documentation of the Configuration File for more information. New collections include those: created during initial sync (page 594), as well as those created by the mongorestore and mongoimport tools, by running mongod with the --repair option, as well as the restoreDatabase command. Chapter 12. Release Notes 854 • Removed upward limit for the maxIncomingConnections for mongod and mongos . Previous versions capped the maximum possible maxIncomingConnections setting at 20,000 connections. • Connection pools for a mongos instance may be used by multiple MongoDB servers. This can reduce the number of connections needed for high-volume workloads and reduce resource consumption in sharded clusters. • The C++ driver now monitors replica set health with the isMaster command instead of replSetGetStatus . This allows the C++ driver to support systems that require authentication. • New cursor.maxTimeMS() and corresponding maxTimeMS option for commands to specify a time limit. • For all new collections on an entire mongod instance, set newCollectionsUsePowerOf2Sizes to false . • For a specific collection, use collMod with usePowerOf2Sizes set to false . • New cleanupOrphaned command to remove orphaned documents from a shard. • New mergeChunks command to combine contiguous chunks located on a single shard. See mergeChunks and Merge Chunks in a Sharded Cluster (page 725). • New rs.printReplicationInfo() and rs.printSlaveReplicationInfo() methods to pro- vide a formatted report of the status of a replica set from the perspective of the primary and the secondary, respectively. Enforce Index Key Length Limit (page 856)