Upgrade from MongoDB Community Edition to Percona Server for MongoDB¶

This document provides instructions for an in-place upgrade from MongoDB Community Edition to Percona Server for MongoDB.

An in-place upgrade is done by keeping the existing data in the server and replacing the MongoDB binaries. Afterwards, you restart the mongod service with the same dbpath data directory.

An in-place upgrade is suitable for most environments except the ones that use ephemeral storage and/or host addresses.

Procedure¶

Note

MongoDB creates a user that belongs to two groups, which is a potential security risk. This is fixed in Percona Server for MongoDB: the user is included only in the mongod group. To avoid problems with current MongoDB setups, existing user group membership is not changed when you migrate to Percona Server for MongoDB. Instead, a new mongod user is created during installation, and it belongs to the mongod group.

This procedure describes an in-place upgrade of a mongod instance. If you are using data at rest encryption, refer to the Upgrading to Percona Server for MongoDB with data at rest encryption enabled section.

Important

Before starting the upgrade, we recommend to perform a full backup of your data.

Upgrade on Debian and Ubuntu Upgrade on Red Hat Enterprise Linux and derivatives

Save the current configuration file as the backup:

$ sudo mv /etc/mongod.conf /etc/mongod.conf.bkp

Stop the mongod service:
```
$ sudo systemctl stop mongod
```

Check for installed packages:

$ sudo dpkg -l | grep mongod

??? example “Sample output”

 ```{.text .no-copy}
 ii  mongodb-org            5.0.2    amd64   MongoDB open source document-oriented database system (metapackage)
 ii  mongodb-org-database   5.0.2    amd64   MongoDB open source document-oriented database system (metapackage)
 ii  mongodb-org-database-tools-extra 5.0.2   amd64   Extra MongoDB database tools
 ii  mongodb-org-mongos     5.0.2    amd64   MongoDB sharded cluster query router
 ii  mongodb-org-server     5.0.2    amd64   MongoDB database server
 ii  mongodb-org-shell      5.0.2    amd64   MongoDB shell client
 ii  mongodb-org-tools      5.0.2    amd64   MongoDB tools
 ```

Remove the installed packages:

$ sudo apt remove \
  mongodb-org \
  mongodb-org-mongos \
  mongodb-org-server \
  mongodb-org-shell \
  mongodb-org-tools

Install Percona Server for MongoDB
Verify that the configuration file includes correct options:
- Copy the required configuration options like custom dbPath/system log path, additional security/replication or sharding options from the backup configuration file (/etc/mongod.conf.bkp) to the current one /etc/mongodb.conf.
- Make sure that the mongod user has access to your custom paths. If not, provide it as follows:
```
$ sudo chown -R mongod:mongod <custom-dbPath>
$ sudo chown -R mongod:mongod <custom-systemLog.path>
```
- Make sure the configuration file includes the following configuration:
```
processManagement:
   fork: true
   pidFilePath: /var/run/mongod.pid
```
  Troubleshooting tip: The pidFilePath setting in mongod.conf must match the PIDFile option in the systemd mongod service unit. Otherwise, the service will kill the mongod process after a timeout.
Restart the mongod service:
```
$ sudo systemctl restart mongod
```

Stop the mongod service:
```
$ sudo systemctl stop mongod
```

Check for installed packages:

$ sudo rpm -qa | grep mongo

??? example “Sample output”

mongodb-org-shell-5.0.2-1.el8.x86_64
mongodb-org-database-5.0.0-1.el8.x86_64
mongodb-org-5.0.0-1.el8.x86_64
mongodb-database-tools-100.4.1-1.x86_64
mongodb-org-server-5.0.2-1.el8.x86_64
mongodb-org-mongos-5.0.2-1.el8.x86_64
mongodb-org-tools-5.0.0-1.el8.x86_64

Remove the installed packages:

$ sudo yum remove \
mongodb-org-tools-5.0.0-1.el8.x86_64 \
mongodb-org-shell-5.0.2-1.el8.x86_64 \
mongodb-org-database-5.0.0-1.el8.x86_64 \
mongodb-org-5.0.0-1.el8.x86_64 \
mongodb-database-tools-100.4.1-1.x86_64 \
mongodb-org-server-5.0.2-1.el8.x86_64 \
mongodb-org-mongos-5.0.2-1.el8.x86_64 \

Install Percona Server for MongoDB
Verify that the configuration file includes correct options:
- When you remove old packages, your existing configuration file is saved as /etc/mongod.conf.rpmsave. Copy the required configuration options like custom dbPath/system log path, additional security/replication or sharding options from the backup configuration file (/etc/mongod.conf.rpmsave) to the current one /etc/mongodb.conf.
- Make sure that the mongod user has access to your custom paths. If not, provide it as follows:
```
$ sudo chown -R mongod:mongod <custom-dbPath>
$ sudo chown -R mongod:mongod <custom-systemLog.path>
```
- Make sure the configuration file includes the following configuration:
```
processManagement:
   fork: true
   pidFilePath: /var/run/mongod.pid
```
  Troubleshooting tip: The pidFilePath setting in mongod.conf must match the PIDFile option in the systemd mongod service unit. Otherwise, the service will kill the mongod process after a timeout.
Restart the mongod service:
```
$ sudo systemctl restart mongod
```

To upgrade a replica set or a sharded cluster, use the rolling restart method. It allows you to perform the upgrade with minimum downtime. You upgrade the nodes one by one, while the whole cluster / replica set remains operational.

Upgrading to Percona Server for MongoDB with data at rest encryption enabled¶

Steps to upgrade from MongoDB 5.0 Community Edition with data encryption enabled to Percona Server for MongoDB are different. mongod requires an empty dbPath data directory because it cannot encrypt data files in place. It must receive data from other replica set members during the initial sync. Please refer to the Switching storage engines for more information on migration of encrypted data. Contact us for working at the detailed migration steps, if further assistance is needed.

Get expert help¶

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