There are a lot of changes that were incorporated into Exchange 2013 both from an Architecture and Operational standpoint. One of these changes is something that can be overlooked very easily so I wanted to point out the reasoning behind this change and what to expect. If you look at the disk space requirements for Exchange 2013 (see below) you will notice we now require 30GB free on the Exchange Install drive. This is a drastic increase from 2010 which only required 1.2GB (which I think was a little on the small side). Although 30GB nowadays isn’t much if you don’t plan for this space increase you could get caught off guard and possibly run into space issues very quickly.
So why do we require all of this extra space? It’s because we now have logging of various Exchange components turned on by default. If you open the logging folder (<Install Drive>\Microsoft\Exchange Server\V15\Logging) on a Mailbox Server check out the amount of folders compared to Exchange 2010.
In all of these folders you will find the corresponding logs for each component. Also if you look in <Exchange Install Drive>\Microsoft\Exchange Server\V15\Logging\Diagnostics\DailyPerformanceLogs you will find Perfmon files (see below) will all of the counters pertaining to Exchange and the Server role (think ExPerfWiz).
Although these log files and Perf data will take up a decent amount of disk space the reasoning behind turning these things on be default was to help customers. If you have had to call into support to troubleshoot an issue you could almost expect the same response every time. After gathering more info on your problem the Engineer would say let’s turn on logging\performance monitor and reproduce the problem. For various reasons customers might not have been able to do this right away. So the Engineer would give the customer an action plan and the customer would call back when they gathered the data. This could be very time consuming and delay getting the problem resolved.
After seeing what kinds of delays this caused the Exchange team decided to collect these logs and performance data by default so it can be used for historical troubleshooting. Instead of having to turn logging on and repro the problem these logs already contain the data we might need. I think this is a great improvement for Exchange 2013 and a welcomed change. I bet most companies are willing to sacrifice a little disk space for hours of support this will save in troubleshooting issues.