MongoDB Documentation, Release 3.0.4 5.4 Production Checklist 5.4.1 Operations Checklist Filesystem Replication 311 5.4. Production Checklist • Verify that all non-hidden replica set members are identically provisioned in terms of their RAM, CPU, disk, network setup, etc. • Configure the oplog size (page 628) to suit your use case: – The replication oplog window should cover normal maintenance and downtime windows to avoid the need for a full resync. – The replication oplog window should cover the time needed to restore a replica set member, either by an initial sync or by restoring from the last backup. • Use hostnames when configuring replica set members, rather than IP addresses. • Ensure that your replica set includes at least three data-bearing nodes with w:majority write concern (page 130). Three data-bearing nodes are required for replica set-wide data durability. • Ensure full bidirectional network connectivity between all mongod instances. • Ensure that each host can resolve itself. • Ensure that your replica set contains an odd number of voting members. • Ensure that mongod instances have 0 or 1 votes. • For high availability, deploy your replica set into a minimum of three data centers. • Align your disk partitions with your RAID configuration. • Avoid using NFS drives for your dbPath . Using NFS drives can result in degraded and unstable performance. See: Remote Filesystems (page 201) for more information. – VMWare users should use VMWare virtual drives over NFS. • Linux/Unix: format your drives into XFS or EXT4. If possible, use XFS as it generally performs better with MongoDB. – With the WiredTiger storage engine, use of XFS is strongly recommended to avoid performance issues found when using EXT4 with WiredTiger. – If using RAID, you may need to configure XFS with your RAID geometry. • Windows: use the NTFS file system. Do not use any FAT file system (i.e. FAT 16/32/exFAT). The following checklists provide recommendations that will help you avoid issues in your production MongoDB deployment. The following checklist, along with the Development (page 314) list, provides recommendations to help you avoid issues in your production MongoDB deployment.