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These are notes we maintain about server migrations under CentOS Linux. In general, we use migrations to a new server when we need a more powerful server to support ever increasing usage, or to do an operating system upgrade. We generally take that opportunity to also update the database, Java and Tomcat versions, though such components are often upgraded in place as well.

NOTE: If you are not upgrading any application components, you only need to rebuild the server and configure the root level systems on the new server and then just copy over all files in the esignforms user account.

Create a new server, generally using the latest version of CentOS (or Red Hat) Linux.

If the new server will use a new IP address when completed, be sure to remember to set the DNS PTR records for the new IP address to point to the server name, and then update the DNS A record after the migration is complete.

If the new server will be able to reuse the original IP address, you generally have to migrate using a new IP address, but when completed, shut down the original server and then reboot your new server using the original IP address (no DNS changes are required).

1. Create the new server using the latest CentOS release. Note the IP address for use in data transfers, as well as root password, to make transfers using scp and rsync easier. Once the migration is complete, root logins and password-based logins are generally disabled.
2. You may want to check the new server IP address to ensure it's not on any anti-SPAM lists if you are using a third-party data center.
3. Follow the basic Linux installation instructions for the initial root steps, but generally don't limit SSH access until the migration is completed. Note that you will use the same hostname as the original server. You may also want to take this opportunity to use new passwords for the root and esignforms (your deployment user account).

Login to the old server as root to copy over files to the new server.

1. rsync -avz -e ssh bin esignforms mycrontab root@NEWIPADDR:.
2. Yozons-specific /usr/local/bin/sp (chmod 755) script for ps
3. Yozons-specific /etc/esfprofile (chmod 640, chown root.esignforms) for offsite backup operations.
4. Add . /etc/esfprofile to .bash_profile
5. Add rm -f ~/.bash_history to .bash_logout
6. Update /etc/postfix/main.cf to include the same entries for mydomain, inet_interfaces, mynetworks_style, home_mailbox and virtual_alias_maps.
7. rsync -avz -e ssh /etc/postfix/virtual_alias root@NEWIPADDR:/etc/postfix/
8. Update /etc/dovecot/dovecot.conf for mail_location and mail_access_groups.
9. For each deployment, create the user account and password to handle in-bound email processing: useradd DEPLOYNAME and passwd DEPLOYNAME.
10. Setup /etc/sysconfig/iptables like the old server, perhaps changing for the new IP address.

Login to the old server as esignforms to copy over files to the new server.

1. rsync -avz -e ssh bashrc bin gpg.howto java mycrontab profile .s3cfg s3cmd.howto s3cmd-VER .ssh tomcat wkhtmltopdf_VER esignforms@NEWIPADDR:.
2. Add . /etc/esfprofile, . ~/profile and . ~/bashrc to .bash_profile
3. Add rm -f ~/.bash_history to .bash_logout
4. mkdir backups, mkdir backups/fullbackup and mkdir backups/tomcat
5. rsync -avz -e ssh postgresql --exclude 'postgresql/data92' esignforms@NEWIPADDR:.
6. rsync -avz -e ssh deployments --exclude 'deployments/*/archive' --exclude 'deployments/*/current' esignforms@NEWIPADDR:.

Login to the old server as esignforms.

Stop the application with yostop all.

Turn off cron jobs: crontab -r (do this for the root too)

Put the 'system down' configuration into place: setWebappsDown

Restart the now-down application: yostart all. The database will be available for backups and the web apps will all report that the service is currently down.

Backup all deployment databases: ~/postgresql/bin/quickbackup

Sync the backups you'd like to move to the new server using something like this:

• rsync -avz -e ssh --include='*/' --include='*.quickdump.YYYYMMDD.gz' --exclude='*' deployments esignforms@NEWIPADDR:.

Stop the database on the old system: yostop db

Login to the new server as esignforms.

Ensure the database is running; if not: yostart db

• Recreate the database for all deployments: ~/postgresql/ddl/recreate_db_only passing in the parameters dbname and dbpassword: i.e. ./recreate_db_only testdb testdbuserpassword
• For each deployment, restore the database backup and run analyze on each database: gunzip -c ~/deployments/DBNAME/archive/db/DBNAME.quickdump.YYYYMMDD.gz | pg_restore -v -d DBNAME
• Generally not required for a simple migraton, but for each deployment, run ~/postgresql/ddl/table_grants DBNAME to ensure the correct permissions on tables and large objects.
• For each deployment, run analyze on the new DB:

  psql DBNAME
  analyze;
  \q
  

Update your DNS for the new IP address.

While logged in as esignforms:

1. Ensure the normal web.xml is in place: setWebappsUp
2. Start Tomcat: yostart web
3. Activate cron jobs: crontab mycrontab

While logged in as root:

1. Activate the cron scripts: crontab mycrontab
2. Install the init script: ./esignforms install
3. Complete any remaining items not done earlier from the basic Linux installation instructions.