Saturday, 7 February 2015

Exchange 2013 - compute resource calculator

Here is a set of calculators for determining compute resource requirements for Exchange 2013:

• Disk IOPS
• Active Directory CPU cores required to support Exchange users
• RAM for Mailbox, CAS, and multi-role server (Mbx+CAS)

A note from Microsoft on the minimum requirements for RAM:

Regardless of whether you are considering a multi-role or a split-role deployment, it is important to ensure that each server has a minimum amount of memory for efficient use of the database cache. There are some scenarios that will produce a relatively small memory requirement from the memory calculations described above. We recommend comparing the per-server memory requirement you have calculated with the following table to ensure you meet the minimum database cache requirements. The guidance is based on total database copies per-server (both active and passive). If the value shown in this table is higher than your calculated per-server memory requirement, adjust your per-server memory requirement to meet the minimum listed in the table.

Per-Server DB Copies
Minimum Physical Memory (GB)


Friday, 6 February 2015

Exchange 2013 - storage space capacity calculator

Here is a nice and quick calculator for a basic estimation of the space capacity required for Exchange databases and logs. It's based on the formulas and recommendations presented by Jeff Mealiffe in Ask the Perf Guy: Sizing Exchange 2013 Deployments.

How to collect the required input data and how it's all calculated is explained here.

The formula for Transport DB size ends with "x 2 copies for high availability". The part in front of it calculates the size of the DB processing active DBs (X), and then this HA part multiplies X with 2 passive copies that protect the system from double server failure. So they multiply the X with 2 HA copies and double it (2X). But if there was only 1 active set of DBs (no DAGs) or 1 copy (A/A or A/P), then X would not change for either 0 HA copies or 1 HA copy. I'm not sure how it doubles with 2 HA copies.

I guess we should calculate the TDB size for active DBs and see what happens after HA copies are added.

Overall Daily Messages Traffic = number of users x message profile

Overall Transport DB Size = average message size x overall daily message traffic x (1 + (percentage of messages queued x maximum queue days) + Safety Net hold days) x 2 copies for high availability

Ask the Perf Guy: Sizing Exchange 2013 Deployments