Upgrading from 6.3 to 7.1 -- how dangerous?

[Doug Hardie]

On Apr 19, 2009, at 10:06, John Almberg wrote:

> I need to upgrade a live, production server from 6.3 to 7.1. I can't  
> afford to have any troubles with this server. I have Absolute  
> FreeBSD and a few other BSD books, and the upgrade process looks  
> fairly straightforward. That's the theory...
>
> Real world question: how scared should I be?

Not at all if you prepare properly (see below).

>
> I've thought about setting up a dummy server, just to practice on.  
> Is this a good idea? Or am I just a nervous Nellie?

That is an excellent approach.  I keep a couple of spare machines  
around just for that purpose.  While most of the update process is  
waiting for things to complete, mergemaster requires a lot of  
responses to a ton of questions about updates to configuration files.   
The vast majority of those will be to install the new version.   
However, there are some where you really need to review the changes  
and make sure your unique configuration gets carried over into the new  
files.  Its really easy to get into the "i" mode and skip right  
through some of those.  The recovery from that will be painful.

Take lots of time on the dummy upgrade to think through the merge and  
keep good records.  You are likely to find that you still have to make  
some changes to those files after the update is complete.  Go back and  
update the records so you don't have to do that a second time on the  
production server.

I also recommend you not let weeks go by between updating the dummy  
and the production systems.  No matter how good you write stuff down,  
some will get forgotten.  Often memory will save you, but if its been  
too long, perhaps not.  The dummy update process will also give you a  
much better estimate of the time you need to have the production  
system down.

I have been using this approach since FreeBSD 2.5 and have had a  
couple of disasters in updating my test system.  After a few retries I  
figured it out and none of the production system updates has  
encountered any issues.  I create a script for each update and save  
them.  Often they come in handy in a later update.  The script is  
really helpful when updating a number of production servers.  I tend  
to forget about some steps otherwise after a few iterations.