Nemo Documentation

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Upgrade from 3.6 to 4.0 ​

In case the system is connected to the internet, create a text file /etc/yum.repos.d/mongodb-org-4.0.repo with the following content (on all the members of the ReplicaSet, in case of such configuration).

[mongodb-org-4.0]
name=MongoDB Repository
baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/4.0/x86_64/
gpgcheck=1
enabled=1
gpgkey=https://www.mongodb.org/static/pgp/server-4.0.asc

In case of an offline installation create the directory mongo-4.0 and put inside the mongo db version 4.0 files.

Standalone upgrade ​

Run the following command as root for the offline installation:

service nemo stop
service mongod stop
cd mongo-4.0
yum upgrade mongodb-*

Run the following commands as root for the online installation:

service nemo stop
service mongod stop
yum upgrade mongodb-org-server

Enable backwards-incompatible 4.0 features ​

Execute the following commands:

# mongo
[...]
> db.adminCommand( { setFeatureCompatibilityVersion: "4.0" } )

ReplicaSet upgrade ​

The upgrade must be done in the right order: first the secondary node(s), then the arbiter, and finally the primary node. Before starting the upgrade, stop the nemo service on all the nodes:

service nemo stop

Secondary node(s) and arbiter upgrade ​

Run the following commands as root for the online installation:

service mongod stop
cd mongo-4.0
yum upgrade mongodb-*

Run the following commands as root for the online installation:

service mongod stop
yum upgrade mongodb-org-server

Verify that mongo is running after the upgrade, and that it is in the right state (see example below):

# mongo
[...]
nemo:SECONDARY>

Primary node upgrade ​

Run the following command as root for the offline installation:

service mongod stop
cd mongo-4.0
yum upgrade mongodb-*

Run the following commands as root for the online installation:

service mongod stop
yum upgrade mongodb-org-server

Enable backwards-incompatible 4.0 features ​

Enable backwards-incompatible 4.0 features Execute the following commands on the primary node:

# mongo
[...]
> db.adminCommand( { setFeatureCompatibilityVersion: "4.0" } )

Verify that mongo is running after the upgrade, and that it is in the right state (see example below):

# mongo
[...]
nemo:SECONDARY>

Test switchover ​

Verify that the switchover works correctly. Connect to the primary node and execute the following command:

# mongo
[...]
nemo:PRIMARY> rs.stepDown()

The primary will become secondary, and the secondary will be elected primary.

Upgrade from 4.0 to 4.2 ​

In case the system is connected to the internet, create a text file /etc/yum.repos.d/mongodb-org-4.2.repo with the following content (on all the members of the ReplicaSet, in case of such configuration).

[mongodb-org-4.2]
name=MongoDB Repository
baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/4.2/x86_64/
gpgcheck=1
enabled=1
gpgkey=https://www.mongodb.org/static/pgp/server-4.2.asc

Also disable the repository of the version 4.0, removing the file /etc/yum.repos.d/mongodb-org-4.0.repo. In case of an offline installation create the directory mongo-4.2 and put inside the mongo db version 4.2 files.

Standalone upgrade ​

Run the following command as root for the offline installation:

service nemo stop
service mongod stop
cd mongo-4.2
yum upgrade mongodb-*

Run the following commands as root for the online installation:

service nemo stop
service mongod stop
yum upgrade mongodb-org-server

Enable backwards-incompatible 4.2 features ​

Execute the following commands:

# mongo
[...]
> db.adminCommand( { setFeatureCompatibilityVersion: "4.2" } )

ReplicaSet upgrade ​

The upgrade must be done in the right order: first the secondary node(s), then the arbiter, and finally the primary node. Before starting the upgrade, stop the nemo service on all the nodes:

service nemo stop

Secondary node(s) and arbiter upgrade ​

Run the following commands as root for the online installation:

service mongod stop
cd mongo-4.2
yum upgrade mongodb-*

Run the following commands as root for the online installation:

service mongod stop
yum upgrade mongodb-org-server

Verify that mongo is running after the upgrade, and that it is in the right state (see example below):

# mongo
[...]
nemo:SECONDARY>

Primary node upgrade ​

Run the following command as root for the offline installation:

service mongod stop
cd mongo-4.2
yum upgrade mongodb-*

Run the following commands as root for the online installation:

service mongod stop
yum upgrade mongodb-org-server

Enable backwards-incompatible 4.2 features ​

Enable backwards-incompatible 4.2 features Execute the following commands on the primary node:

# mongo
[...]
> db.adminCommand( { setFeatureCompatibilityVersion: "4.2" } )

Verify that mongo is running after the upgrade, and that it is in the right state (see example below):

# mongo
[...]
nemo:SECONDARY>

Test switchover ​

Verify that the switchover works correctly. Connect to the primary node and execute the following command:

# mongo
[...]
nemo:PRIMARY> rs.stepDown()

The primary will become secondary, and the secondary will be elected primary.

Upgrade from 4.2 to 4.4 ​

In case the system is connected to the internet, create a text file /etc/yum.repos.d/mongodb-org-4.4.repo with the following content (on all the members of the ReplicaSet, in case of such configuration).

[mongodb-org-4.4]
name=MongoDB Repository
baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/4.4/x86_64/
gpgcheck=1
enabled=1
gpgkey=https://www.mongodb.org/static/pgp/server-4.4.asc

Also disable the repository of the version 4.2, removing the file /etc/yum.repos.d/mongodb-org-4.2.repo. In case of an offline installation create the directory mongo-4.4 and put inside the mongo db version 4.4 files.

Standalone upgrade ​

Run the following command as root for the offline installation:

service nemo stop
service mongod stop
cd mongo-4.4
yum upgrade mongodb-*

In case the command fails due to missing dependencies of cyrus packages, run the following:

yum install cyrus*

Then repeat again the command

yum install mongodb-*

Run the following commands as root for the online installation:

service nemo stop
service mongod stop
yum upgrade mongodb-org-server

Disable fork configuration ​

Mongodb 4.4 will not start up if the fork: enable command is configured in the /etc/mongod.conf file. To remove the fork: true configuration, run the following commands

sed -i.bak '/fork: true/d' /etc/mongod.conf
systemctl start mongod.service

At this point, mongod process should be running and stable.

Enable backwards-incompatible 4.4 features ​

Execute the following commands:

# mongo
[...]
> db.adminCommand( { setFeatureCompatibilityVersion: "4.4" } )

ReplicaSet upgrade ​

The upgrade must be done in the right order: first the secondary node(s), then the arbiter, and finally the primary node. Before starting the upgrade, stop the nemo service on all the nodes:

service nemo stop

Secondary node(s) and arbiter upgrade ​

Run the following commands as root for the online installation:

service mongod stop
cd mongo-4.4
yum upgrade mongodb-*

In case the command fails due to missing dependencies of cyrus packages, run the following:

yum install cyrus*

Then repeat again the command

yum install mongodb-*

Run the following commands as root for the online installation:

service mongod stop
yum upgrade mongodb-org-server

Disable fork cofiguration ​

Mongodb 4.4 will not start up if the fork: enable command is configured in the /etc/mongod.conf file. To remove it, run the following commands:

sed -i.bak '/fork: true/d' /etc/mongod.conf
systemctl start mongod.service

At this point, mongod process should be running and stable.

Verify that mongo is running after the upgrade, and that it is in the right state (see example below):

# mongo
[...]
nemo:SECONDARY>

Primary node upgrade ​

Run the following command as root for the offline installation:

service mongod stop
cd mongo-4.4
yum upgrade mongodb-*

In case the command fails due to missing dependencies of cyrus packages, run the following:

yum install cyrus*

Then repeat again the command

yum install mongodb-*

Run the following commands as root for the online installation:

service mongod stop
yum upgrade mongodb-org-server

Disable fork cofiguration ​

Mongodb 4.4 will not start up if the fork: enable command is configured in the /etc/mongod.conf file. To remove the fork: true configuration, run the following commands

sed -i.bak '/fork: true/d' /etc/mongod.conf
systemctl start mongod.service

At this point, mongod process should be running and stable.

Enable backwards-incompatible 4.4 features ​

Execute the following commands on the primary node:

# mongo
[...]
> db.adminCommand( { setFeatureCompatibilityVersion: "4.4" } )

Verify that mongo is running after the upgrade, and that it is in the right state (see example below):

# mongo
[...]
nemo:SECONDARY>

Test switchover ​

Verify that the switchover works correctly. Connect to the primary node and execute the following command:

# mongo
[...]
nemo:PRIMARY> rs.stepDown()

The primary will become secondary, and the secondary will be elected primary.

Upgrade from 4.4 to 5.0 ​

In case the system is connected to the internet, create a text file /etc/yum.repos.d/mongodb-org-5.0.repo with the following content (on all the members of the ReplicaSet, in case of such configuration).

[mongodb-org-5.0]
name=MongoDB Repository
baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/5.0/x86_64/
gpgcheck=1
enabled=1
gpgkey=https://www.mongodb.org/static/pgp/server-5.0.asc

Also disable the repository of the version 4.4, removing the file /etc/yum.repos.d/mongodb-org-4.4.repo. In case of an offline installation create the directory mongo-5.0 and put inside the mongo db version 5.0 files.

Standalone upgrade ​

Run the following command as root for the offline installation:

service nemo stop
service mongod stop
cd mongo-5.0
yum upgrade mongodb-*

Run the following commands as root for the online installation:

service nemo stop
service mongod stop
yum upgrade mongodb-org-server mongodb-org-shell mongodb-org-mongos mongodb-org mongodb-org-database-tools-extra mongodb-org-tools mongodb-mongosh mongodb-org-database mongodb-database-tools

Disable enableMajorityReadConcern configuration ​

Mongodb 5.0 will not start up if the enableMajorityReadConcern is configured: the option is no more necessary, since the write concern is set to majority by default. To remove it, run the following commands

sed -i.bak '/enableMajorityReadConcern: false/d' /etc/mongod.conf
systemctl start mongod.service

At this point, mongod process should be running and stable.

Enable backwards-incompatible 5.0 features ​

Execute the following commands:

# mongo
[...]
> db.adminCommand( { setFeatureCompatibilityVersion: "5.0" } )

Configure the default read and write concern ​

Execute the following commands:

# mongo
[...]
db.adminCommand({
   "setDefaultRWConcern" : 1,
   "defaultWriteConcern" : {
     "w" : 1
   }
 })

ReplicaSet upgrade ​

The upgrade must be done in the right order: first the secondary node(s), then the arbiter, and finally the primary node. Before starting the upgrade, stop the nemo service on all the nodes:

service nemo stop

Secondary node(s) and arbiter upgrade ​

Run the following commands as root for the online installation:

service mongod stop
cd mongo-5.0
yum upgrade mongodb-*

Run the following commands as root for the online installation:

service mongod stop
yum upgrade mongodb-org-server mongodb-org-shell mongodb-org-mongos mongodb-org mongodb-org-database-tools-extra mongodb-org-tools mongodb-mongosh mongodb-org-database mongodb-database-tools

Disable enableMajorityReadConcern configuration ​

Mongodb 5.0 will not start up if the enableMajorityReadConcern is configured: the option is no more necessary, since the write concern is set to majority by default. To remove it, run the following commands

sed -i.bak '/enableMajorityReadConcern: false/d' /etc/mongod.conf
systemctl start mongod.service

At this point, mongod process should be running and stable.

Verify that mongo is running after the upgrade, and that it is in the right state (see example below):

# mongo
[...]
nemo:SECONDARY>

Primary node upgrade ​

Run the following command as root for the offline installation:

service mongod stop
cd mongo-5.0
yum upgrade mongodb-*

Run the following commands as root for the online installation:

service mongod stop
yum upgrade mongodb-org-server mongodb-org-shell mongodb-org-mongos mongodb-org mongodb-org-database-tools-extra mongodb-org-tools mongodb-mongosh mongodb-org-database mongodb-database-tools

Disable enableMajorityReadConcern configuration ​

Mongodb 5.0 will not start up if the enableMajorityReadConcern is configured: the option is no more necessary, since the write concern is set to majority by default. To remove it, run the following commands

sed -i.bak '/enableMajorityReadConcern: false/d' /etc/mongod.conf
systemctl start mongod.service

At this point, mongod process should be running and stable.

Enable backwards-incompatible 5.0 features ​

Execute the following commands on the primary node:

# mongo
[...]
> db.adminCommand( { setFeatureCompatibilityVersion: "5.0" } )

Verify that mongo is running after the upgrade, and that it is in the right state (see example below):

# mongo
[...]
nemo:SECONDARY>

Configure the default read and write concern ​

Execute the following commands:

# mongo
[...]
db.adminCommand({
   "setDefaultRWConcern" : 1,
   "defaultWriteConcern" : {
     "w" : 1
   }
 })

Test switchover ​

Verify that the switchover works correctly. Connect to the primary node and execute the following command:

# mongo
[...]
nemo:PRIMARY> rs.stepDown()

The primary will become secondary, and the secondary will be elected primary.