Changing MongoDB storage engine from Mmapv1 to WiredTiger

Changing the storage engine for a standalone MongoDB server from Mmapv1 to WiredTiger is relatively painless.

Here’s how I did it.

Backup the database
```
mongodump --out /srv/backup/mongodb
```
Stop monbodb service
```
service mongodb stop
```

Update mongodb.conf. Here’s my /etc/mongodb.conf file:

# mongod.conf

storage:
  dbPath: "/var/lib/mongo" 
  engine: wiredTiger
  wiredTiger:
    engineConfig:
      cacheSizeGB: 1
      statisticsLogDelaySecs: 0
      journalCompressor: snappy
      directoryForIndexes: false
    collectionConfig:
      blockCompressor: snappy
    indexConfig:
      prefixCompression: true

systemLog:
  verbosity: 1
  path: "/var/log/mongodb/mongod.log" 
  logAppend: true
  logRotate: reopen
  destination: file
  timeStampFormat: iso8601-utc

processManagement:
  fork: true
  pidFilePath: "/var/run/mongodb/mongod.pid" 

net:
  bindIp: 127.0.0.1
  port: 27017
  wireObjectCheck: false
  unixDomainSocket:
    enabled: true

Start monbodb service
```
service mongodb start
```
Restore the database from backup
```
mongorestore /srv/backup/mongodb
```

That’s it.

To check what storage engine you’re using with your MongoDB, connect to the mongodb with mongo shell and run:

> db.serverStatus().storageEngine
{ "name" : "wiredTiger" }