During TechEd 2010 in New Orleans I was able to attend a session dealing with the CAS workload Sizing.  Microsoft put together a new chart to help with the different workloads that hit a CAS.  The chart is based on the amount of workload that a typical CAS will see and the CPU Cost and Network Cost.  I have attached a copy of the Chart that MS will be publishing to help with CAS sizing in the future.  The chart is based on a 100 messages sent/received per day. 

The Chart:

The chart gives a potential impact of using all Outlook using in the form of Outlook Anywhere, Outlook Web Application, Outlook, and ActiveSync.  You can see that the chart includes IMAP and POP3 but those protocols are used for reading and not submitting mail.    

If you take a look at the chart you will notice that Outlook Anywhere and Outlook Web App are basically the same thus simplifying the sizing used for those roles.  ActiveSync is actually an additional cost to Outlook.  The logic here is that users will both be using Outlook and ActiveSync at the same time.  Rarely do you see a user just using ActiveSync and not use Outlook at any given time during the day.  (Actually I’m using Outlook right now and ActiveSync since my phone is automatically syncing) 

Another key take away from this session is the use of Windows 2008 R2.  It was mentioned that the improvements to Windows 2008 R2’s rpcproxy service allows for the expansion of 15,000 Outlook Anywhere users on an 8-core CAS i.e. 2 sockets with 4 cores each (Recall my previous post?)

Anyway, I felt this chart was very useful and since it hasn’t been published on TechNet yet I thought I would share.

Enjoy!