Upgrade RT from 3.8.8 to 4.0.6


I want to upgrade our production RT v3.8.8 to the latest v4.0.6. I un-tarred the RT 4.0.6 kit in /opt/rt-4.0.6.
on our production RT box. I want to be able to revert back to our current production RT v3.8.8 system if
something goes wrong. I also am willing to build a new machine for RT 4.0.6 to make a clean install and separation
between RT 3.8.8 and RT 4.0.6, but that causes some possible extra work to our email/dns/apache setup.

I have a few questions about the upgrade:

  1. RT 4.0.6 complains about several missing perl modules when I run “make testdeps”.
    on the production RT machine. If I then run “make fixdeps” in /opt/rt-4.0.6 and install the missing modules,
    this will not break the existing production RT 3.8.8 running on the machine, correct ? Or will it ? This is the key
    to using the existing production box, or to installing on a brand new machine. We can’t break the existing
    production RT system.

  2. Although this is an upgrade to 4.0.6, I don’t wish to touch any of /opt/rt-3.8.8 so what I am doing
    is a “new install” and it will install by default into /opt/rt4 I believe. This won’t touch the 3.8.8 software correct ?

  3. When upgrading the RT database, I will dump the existing production database and load it into a different
    mysql server for v4.0.6 because the existing mysql server is old.

When running the following commands below in /opt/rt-4.0.6, on the production box, it will look at the settings in
/opt/rt4/etc/RT_SiteConfig.pm pointing to the new mysql server, and not what’s set in /opt/rt-3.8.8/etc/RT_SiteConfig.pm
which points to the existing production mysql sever, correct ? I don’t want to touch the existing production mysql database.

make upgrade-database
perl etc/upgrade/vulnerable-passwords
perl -I /opt/rt4/local/lib -I /opt/rt4/lib etc/upgrade/shrink_transactions_table.pl

I’m going back and forth on what is the best path to go, install on the existing production server or install it on a
separate new machine which gives a way to revert back to RT 3.8.8. What do you recommend ?

Thanks in advance,