Massive upgrades (WAS: Physical Memory Fully Used...)
Date: Tue, 23 Jun 2009 09:28:55 -0500 (CDT)
>> It was a very bad decision to change everything at one time as well (not
>> decision) --definitely not a best practice to change everything without
>> testing, testing, testing and then testing again.
As with most things, it depends. I was on a project a few years back where the hardware, OS, and Oracle versions all were intertwined to the point where upgrading one (the hardware) necessitated the rest. We needed to upgrade the hardware, but the minimum OS version was well beyond where we were, and that OS version no longer was supported for our version of Oracle.
And, of course, this resulted in requiring the complete recompilation of all ~7000 ERP 4GL programs -- something we'd never done before. Did I mention that we implemented LDAP here as well?
In the three months our spartan IS team had to do this conversion there was a lot of testing, a lot of swearing, and a few tempers. But come go-live, the biggest issues we generally had were printer definitions not coming over to the new server and some security issues related to LDAP logins. An informal survey of users I knew well were so happy with the speed of the new system that they didn't mind a half day with minor interruptions.
I wouldn't recommend changing everything at once (glibc dependencies can be a challenge to unravel!), but if it's required it certainly can be accomplished.