Ubuntu – Startup warnings after upgrading from MongoDB 2.6 to 3.4

mongodb

I removed MongoDB 2.6 and installed MongoDB 3.4. When I connect to the MongoDB 3.4 server there are several new startup warnings:

MongoDB shell version v3.4.2
connecting to: mongodb://127.0.0.1:27017
MongoDB server version: 3.4.2
Server has startup warnings: 

2017-03-20T20:27:36.175+0545 I STORAGE  [initandlisten]     
2017-03-20T20:27:36.175+0545 I STORAGE  [initandlisten] ** WARNING: Using the XFS filesystem is strongly recommended with the WiredTiger storage engine
2017-03-20T20:27:36.175+0545 I STORAGE  [initandlisten] **          See http://dochub.mongodb.org/core/prodnotes-filesystem
2017-03-20T20:27:36.855+0545 I CONTROL  [initandlisten] 
2017-03-20T20:27:36.855+0545 I CONTROL  [initandlisten] ** WARNING: Access control is not enabled for the database.
2017-03-20T20:27:36.855+0545 I CONTROL  [initandlisten] **          Read and write access to data and configuration is unrestricted.
2017-03-20T20:27:36.855+0545 I CONTROL  [initandlisten] 
2017-03-20T20:27:36.855+0545 I CONTROL  [initandlisten]
2017-03-20T20:27:36.855+0545 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2017-03-20T20:27:36.855+0545 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2017-03-20T20:27:36.855+0545 I CONTROL  [initandlisten] 
2017-03-20T20:27:36.855+0545 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.   
2017-03-20T20:27:36.855+0545 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2017-03-20T20:27:36.855+0545 I CONTROL  [initandlisten]

How do I remove these warnings?

Best Answer

The MongoDB 3.4 log messages you have highlighted are startup warnings, not errors. These warnings are intended to alert administrators to configuration settings that may have potentially detrimental impact (particularly for production deployments).

If this is a development environment (or you are not concerned about maximizing performance) you can choose to ignore these.

For a more detailed list of recommended settings you should review the Production Notes in the MongoDB manual. Successive versions of MongoDB have added more server warnings for detectable configuration settings as many administrators are unaware of the production notes or what may apply to their deployment.

WARNING: Using the XFS filesystem is strongly recommended with the WiredTiger storage engine

This warning indicates you are using WiredTiger and a filesystem other than XFS (see http://dochub.mongodb.org/core/prodnotes-filesystem for more information).

WARNING: Access control is not enabled for the database.

This warning indicates you do not have access control enabled, so any user/application that can connect to your deployment will have unrestricted access. To secure your deployment please review the measures in the MongoDB Security Checklist.

WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.

We suggest setting it to 'never'

WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.

We suggest setting it to 'never'

Transparent Huge Pages (THP) is a Linux memory management setting that can adversely affect database workflows. For more information see: Disable Transparent Huge Pages in the MongoDB manual.

Related Solutions

Ubuntu – MongoDB 2.6 does not start on Ubuntu 15.04

I installed from the debian wheeze repository and it works fine.

First make sure you remove the mongodb-org package and all its dependencies:

sudo apt-get purge mongodb-org
sudo apt-get autoremove

Remove the old mongodb.list you created:

sudo rm /etc/apt/sources.list.d/mongodb.list

Use the Debian repository instead:

echo "deb http://repo.mongodb.org/apt/debian wheezy/mongodb-org/3.0 main" | sudo tee /etc/apt/sources.list.d/mongodb-org-3.0.list

Update and install again:

sudo apt-get update
sudo apt-get install -y mongodb-org

After that, you can succesffully start the server:

sudo service mongod start

systemctl start mongod

(as clarified by Ernie Hershey in reply to Roman Gaufman's comment here: https://jira.mongodb.org/browse/SERVER-17742)

Ubuntu – How to migrate MongoDB 2.6 to 3.0 with WiredTiger

In default installations, the configuration file is at /etc/mongod.conf. What the MongoDB docs don't mention is that when migrating to WiredTiger we also need to update the configuration file to the new YAML format introduced in 2.6.
As far as I can tell the engine option is only available in the new configuration format.
Migrating from the old storage engine consists in creating a database dump, shutting down mongodb, changing settings and then importing the dump into the new storage engine.

Create a backup. Seriously. We need a database dump which we'll then import to the new database engine:
```
mongodump -d db_name /backup/path/  
```
Stop the mongodb service
```
sudo service mongod stop  
```
Move data from the current location to somewhere else (MongoDB will not startup if the data directory contains files generated by the old storage engine).
```
sudo mv /var/lib/mongodb /var/lib/mongodb_26/
```

Upgrade MongoDB to version 3.0 (from http://docs.mongodb.org/v3.0/tutorial/install-mongodb-on-ubuntu/):

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10  
echo "deb http://repo.mongodb.org/apt/ubuntu "$(lsb_release -sc)"/mongodb-org/3.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-3.0.list  
sudo apt-get update  
sudo apt-get install mongodb-org mongodb-org-server mongodb-org-shell mongodb-org-mongos mongodb-org-tools

Convert the configuration file from old (pre 2.6) to the current YAML format. The bare minimum is:

storage:  
    dbPath: "/var/lib/mongodb"  
    engine: wiredTiger  

systemLog:  
   destination: file  
   path: "/var/log/mongodb/mongod.log"  
   logAppend: true  

net:  
    bindIp: 127.0.0.1  
    port: 27017  
    # Enable the HTTP interface (Defaults to port 28017).  
    http:  
        enabled: false

Make sure no lines in the old format remain, or MongoDB won't start.

The full documentation for the configurtion file is at: http://docs.mongodb.org/v3.0/reference/configuration-options/

Optionally make a backup of the log:

sudo mv /var/log/mongodb/mongod.log /var/log/mongodb/mongod_26.log

Restart mongodb
```
sudo service mongod start
```
Load the backup to convert data to new storage engine
```
mongorestore /backup/location
```

After checking that all your data is ok, you can delete the directory with the old data format

sudo rm -r /var/lib/mongodb_26/

Note that for replica sets and sharded clusters there are some aditional steps: http://docs.mongodb.org/v3.0/release-notes/3.0-upgrade/?_ga=1.86531032.1131483509.1428671022#change-replica-set-storage-engine-to-wiredtiger

Best Answer

Related Solutions

Ubuntu – MongoDB 2.6 does not start on Ubuntu 15.04

Ubuntu – How to migrate MongoDB 2.6 to 3.0 with WiredTiger

Related Question