Imagine that you’re an eager young race car driver. You seek out the advice of a more experienced driver about the characteristics of your car, following his advice to the letter. Later that year, you both enter the same race. As you approach your vehicle, something catches your eye and leaves you baffled. Why doesn’t your mentor’s car contain the same half ton of bricks he recommended for “cornering stability”?
Whether intentional or not, the Exchange mailbox role calculator sets up on-premises providers to fail in a very similar way.
The case of the 50GB mailbox
Office 365 now comes with a 50GB mailbox limit (although others offer unlimited mailboxes). According to the mailbox calculator, that 50GB mailbox will occupy 77GB of database capacity in each copy, and four of them totals out to 308GB. It would be nuts to allocate all that capacity every time a
user customer orders a plan, because only a tiny fraction of them will ever even approach that limit. Instead, all SaaS providers deploy the mailbox and then monitor it, leveraging a set of automated processes to smooth out capacity utilization. You know, elastic computing. Cloud stuff.
This is exactly opposite of what the Mailbox role calculator assumes.
Better buy all that up front, cowboy!
This is problematic because Microsoft is providing design guidance to their competitors (on-prem IT shops) that Microsoft itself doesn’t follow. Admittedly, this is a dim view of Microsoft’s motivations – they might not actually be trying to position themselves ahead of on-premises IT shops. A more charitable perspective is that this advice insulates Microsoft from liability for undersized environments. But regardless of the motivations, it’s inadvisable to ignore the disadvantages that Microsoft’s design guidance presents to on-prem IT shops as they compete for the very same business.
Quotas are guardrails
I believe if more than 5% of your
users customers ever hit their quota, you’ve set them too small. It’s likely a good number of people who approach their quota limits set up PSTs so that they can continue to work. And no matter your group policies, it’s really difficult (impossible?) to prevent self-archiving. So you’ve probably got data governance issues that dwarf storage cost. Instead of using quotas to modify user customer behavior, treat your quotas as guardrails – the last line of defense against rogue applications and viruses that fill mailboxes (and the disks they sit on).
Now, if all your customers hit their quota AT THE SAME TIME (as the mailbox sizer assumes), well, let’s just say your quotas are way, way too small.
So what’s the solution? Provide your
users customers with unlimited mailboxes. If you’ve got more than a couple hundred customers, it’s really easy to size against actual utilization. You have the data at hand to do this. There are tons of powershell scripts to give you the information you need to put a sensible number into that calculator, and should differ significantly from the quota. Run it once at the beginning of a month, again at the end, and with some excel magic you can not only get what you’re using today, but what you’ll need a year from now. You can apply simple statistical calculations like percentiles and standard deviation to figure out where your outliers are likely to sit. Go crazy with it – no matter what you do, it’ll be far better than trying to size against your most deviant group of customers.
You provide your
users customers with unlimited mailboxes, and you don’t have to worry about that rogue PST, or people archiving off to their local disk as they are wont to do when presented with quotas. Your legal department will thank you.
You’ll also be in a good position to compete with cloud solutions from both an economic and feature perspective. For what it’s worth, EMC provides its 60k+ customers with a 99.99% available solution, with unlimited mailboxes, legal hold, and geo-redundancy for less than $16 per customer per month,including labor, at list price for the hardware and software.