Ideally, you need to stay up to date. Old versions of packages tend to become security risks as holes are discovered in the code. Also, as time passes you'll find trouble running newer software on an older environment (e.g. You have have a webapp the requires PHP5, but you only have 4. Unlikely in the short term, since PHP5 is still quite new, but how about 2 years from now?)
In some cases (leased server with no physical access) upgrading is impossible without the assistance of your colocation provider. In these cases, I tend to compile the critical software from source myself so I can stay up to date. It's not a perfect solution, or even a terribly good one, but I've had success with it on the small scale.
|