CommonStore Solution Sizing Basics

Published 29 December 2006

Authors: Wei-Dong Zhu


This document introduces the basics of sizing a CommonStore solution. We cover the key information that is used for sizing and introduce some of the best practices for CommonStore solution sizing.


Sizing is an approximation of the hardware resources required to support a specific software implementation. It is based on information available at a point in time and provides an entry to understanding the hardware requirements.

To perform sizing exercises for CommonStore solutions, use the sizing tool as a starting point. The CommonStore sizing tool (also known as sizer) contains a set of calculations based on benchmark workloads developed and tested by the development lab in tuned systems in a lab environment. Using these numbers and the information that you provide, it estimates the hardware resources that are required to fulfill your business requirements.

The key input information required by the CommonStore sizing tool includes the following:

  • The total number of unique e-mails that your system must be able to archive each day and within what specified time period

    This information helps you to calculate the number of central processing units (CPUs) required for each software component and the number of CommonStore servers that your solution requires.

  • Current average e-mail size (including attachments), the projected growing rate each year, and the retention policy of the archived e-mails

    This information helps you to calculate the disk space storage size (used for the databases, objects, and index files) that your solution requires today and for subsequent years.

We recommend the following best practices when sizing for a CommonStore solution:
  • Always calculate the disk space requirement over several years so that you have a better picture of the overall hardware requirement.
  • Always get a machine that has at least certain standard CPU power and speed and still has the capacity to grow so that you can add more CPUs and disk spaces later when necessary. Do not size a machine that can accommodate only your first year CommonStore solution requirements. For example, if according to sizing, you only require an AIX machine with two CPUs for Content Manager, we recommend that you start with a standard AIX machine with four CPUs.
  • If your company already uses machines that have more processing power, more memory, or more CPUs than the required machines from the sizing calculation, use the same type of machines you currently have in the company, if it is possible and feasible.
  • When sizing a very large system for long-term retention and discovery, plan to spread data across multiple item types. eMail Search supports this feature. We recommend that you do not exceed more than 1 TB in an index. Check with the IBM lab consultants for the latest recommendation to handle large volume e-mails.

For more information regarding CommonStore solution sizing, refer to Chapter 4 "Sizing" of the IBM Redbook, Best Practices for Setting Up an IBM CommonStore Solution For Mailbox Management, e-Mail Retention and Discovery, SG24-7325. There is also a sizer for CommonStore with eMail Search that you can download along with the book.

Disclaimer: Use the sizing tool to understand how sizing can be done. Do not use it without consulting the IBM specialists in this area. Always check with the Content Management lab for the most up-to-date sizer if you are eligible to obtain one. The lab continues to gather data to refine these calculations. Use the formulas that we provide here to get an idea of how sizing works. Do not use the sizing tool as is.

Special Notices

This material has not been submitted to any formal IBM test and is published AS IS. It has not been the subject of rigorous review. IBM assumes no responsibility for its accuracy or completeness. The use of this information or the implementation of any of these techniques is a client responsibility and depends upon the client's ability to evaluate and integrate them into the client's operational environment.

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