In a related note to the backup restore that I performed yesterday, I decided to run the upgrade.sh script provided by community.aegir.com.
First, I downloaded the script to my restored EC2 instance
wget -O upgrade.sh 'http://drupalcode.org/project/provision.git/blob_plain/refs/tags/6.x-1.6:/upgrade.sh.txt'
Next I logged in as the Aegir user and ran the uprade.sh script per the instructions:
su -s /bin/sh aegir -c "sh upgrade.sh"
The status message displayed mentioned that drush could not be manually updated due to a permission error. It seems the Aegir user didn't have access to drush.
aegir@ip-10-190-231-119:~$ sh upgrade.sh
==> Drush found in /vol/aegir/drush/drush.php, good
==> Aegir 6.x-1.6 automated upgrade script
==> This script makes the following assumptions:
* you have read http://community.aegirproject.org/upgrading and have prepared the server accordingly
* you are executing this script as your "aegir" user
* that the following settings are correct
The Aegir version to upgrade to is 6.x-1.6
The Aegir home dir is /vol/aegir
The new hostmaster platform will be /vol/aegir/hostmaster-6.x-1.6
Your Aegir domain is ec2-75-101-211-245.compute-1.amazonaws.com
Your old hostmaster platform was /vol/aegir/hostmaster-6.x-1.6
The Drush command is "php /vol/aegir/drush/drush.php"
The version of Drush will be 7.x-4.5
The version of Drush Make will be 6.x-2.3
Do you want to proceed with the upgrade? [Y/n]
Next, I logged back in a the Ubuntu user and moved Drush (/usr/local/drush) to (/vol/aegir/drush). Then I changed the /vol/aegir/drush to be owned by aegir:aegir.
Then I logged back in as the Aegir user and added a new alias with the new path to drush:
Then I ran the upgrade.sh script again and everything seemed to go smoothly.