Scaling Memcached

Create a New EC2 Instance

1. Launch a new EC2 instance from the AMI

   1. Login in to AWS account.

   2. Select Launch Instance.

      

   3. Select Image "Ubuntu Server 20.04 LTS (HVM), SSD Volume Type.

      

   4. Select t2.medium.

      

   5. Add Storage >Enter 30GB

      

   6. Configure Security Group

      

Install memcached

1. Access the memcache server through ssh from terminal.

2. Execute the following commands.

    sudo apt update
    sudo apt install memcached
    sudo apt install libmemcached-tools
   

3. Configure memcached to accept remote connections.

   1. Edit the file /etc/memcached.conf on or around row 35 as follows:

      nano /etc/memcached.conf

      Change the "-l 127.0.0.1" with "-l 0.0.0.0"

   

4. Reboot the remote Memcached server

    sudo reboot
   

Reconfigure Open edX to Connect to Your Remote Memcached Serve

1. Access the OpenEdx server through ssh from terminal.

2. Modify memcached host settings

   1. Get the files where memcached is configured to do this use the following grep command

       sudo grep -r '11211' /edx/etc/*.yml
      

   

   In total there are 4 files with memcache is set.

   1. Access each file using nano

       nano /edx/etc/lms.yml
       nano /edx/etc/studio.yml
       sudo nano /edx/etc/ecommerce.yml
       sudo nano /edx/etc/insight.yml
      

      Example of lms.yml

      

      Replace the "localhost" or "127.0.0.1" with the memcache server Private IP in all the 4 files.

      

      Updated lms.yml

      

   2. Stop the memcached service on your edxapp server.

       sudo service memcached stop
       sudo systemctl disable memcached
      

   3. Do a full reboot of your OpenEdx Ubuntu server when you finish.

       sudo reboot
      

Test Your Changes

1. Check memcached status locally.

   1. Access the memcache server through ssh from terminal.

       echo stats | nc 127.0.0.1 11211
       memcstat --servers=127.0.0.1 11211
      

      

2. Check memcached status remotely from openedx server.

   1. Access the OpenEdx server through ssh from terminal.

       echo stats | nc 172.x.x.x 11211
       memcstat --servers=172.x.x.x 11211