Disable THP on Linux machines to ensure best performance with MongoDB

Add the script

(1) Move the file named disable-transparent-hugepages to /usr/bin/

(2) Ensure ownership of root:root for the file

(3) Ensure permissions of 0755 for the file

Add the service

(4) Copy the file named disable-transparent-hugepages.service to /etc/systemd/system/

(5) Ensure ownership of root:root for the file

(6) Ensure permissions of 0644 for the file

(7) Run systemctl daemon-reload

(8) Run systemctl enable disable-transparent-hugepages

(9) Run systemctl start disable-transparent-hugepages

Set THP

(9) Create a new path with sudo mkdir /etc/tuned/no-thp/

(10) Copy the file named tuned.conf to /etc/tuned/no-thp/

(11) Run tuned-adm profile no-thp

Testing

(12) Run cat /sys/kernel/mm/transparent_hugepage/enabled

(13) Run cat /sys/kernel/mm/transparent_hugepage/defrag

(14) Both commands should produce this: always madvise [never]

Rollback MongoDB from 4.0.5 to 3.6.9

Pre-req #1: Back up the database

Pre-req #2: Shut down all LAs

(1) Check current featureCompatibility version (This may return a blank value)

db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )

(2) Run db.adminCommand({setFeatureCompatibilityVersion: "3.6"})

(3) Check it again for sanity: db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )

(4) Restart mongo 4.0 so that it starts up in compatibility mode: sudo service mongod restart

(5) Shut it down again and check that mongo is shut down:

sudo service mongod stop

systemctl status mongod

(6) Uninstall Mongo 4.0.5

rpm -qa | grep mongo

sudo rpm -ev mongodb-org-4.0.5-1.el7.x86_64

sudo rpm -ev mongodb-org-mongos-4.0.5-1.el7.x86_64

sudo rpm -ev mongodb-org-server-4.0.5-1.el7.x86_64

sudo rpm -ev mongodb-org-shell-4.0.5-1.el7.x86_64

sudo rpm -ev mongodb-org-tools-4.0.5-1.el7.x86_64

Check that all packages are removed: rpm -qa | grep mongo

(7) Install 3.6.9. Download all packages and run: sudo rpm -i mongodb-org*.rpm