Sizing the Cognos Content Store

By Paul Hausser, Envisn, Inc.
The single biggest issue for many Cognos administrators is the out-of-control growth of their Cognos Content Store. This usually happens after the environment has been operational for a while but it’s worth knowing what is assumed to be behind the growth of the Content Store.

Sizing Metrics

There are a number of factors that IBM Cognos recommends using for sizing the Cognos Content Store. These include:

• Number of users
  This is a primary driver; the more users the more reports and queries are typically run.
• Number of saved reports
  The larger the number of saved reports, the greater the space required.
• Number of saved views
  The greater the number of report views saved, the greater the space required.
• Number of folders
  Cognos BI typically uses public folders as well as one or more private folders for each user.
• Number of schedules
  There can be schedules for daily, weekly, and monthly runs. The greater the number of schedules, the greater the Content Store space required.
• Number of Framework Manager packages
  The greater the number of packages, and the number of tables and query subjects in those packages, the greater the space required.
• Additional storage items
  Additional storage items such as transaction logs and temporary space requirements increase the size of the Content Store required.

All of this is pretty straight forward and Cognos provides guidelines for each of these categories that can be found here. The next step is to just extend these out using your own estimates for users, reports, packages, etc. What you will notice if you look at these guidelines carefully is that, even with fairly modest assumptions about the number of users, numbers of reports and views per user, size of reports, etc., the size of the Content Store at inception can be reasonably large. And in many environments today it’s growing at rates that administrators find hard to understand.

Finding Your Own Growth Drivers

The IBM Content Manager Browser Tool was an attempt to provide Cognos administrators with a tool that could help them manage their Cognos environments. Introduced over four years ago, its user interface is somewhat clunky in terms of getting needed data and being able to analyze it easily. Administrators need to be able track and analyze multiple metrics around their Content Store and determine what the actual drivers are for their own environment. This starts with being able to get data on:

• Size of the Content Store
• Make-up of object count
• Amount of saved output
• Rates of growth
• Areas of growth
• Usage (both user and content)

With real data administrators can begin to identify specific drivers unique to their environment. Simply by tracking this data over fixed points in time you’ll be able to identify relationships between key variables. With this you can then identify how these relationships change and from this begin to make some assumptions about actual drivers. Getting the appropriate level of detail is important and having a product like NetVisn can make it easier if the IBM tool doesn’t do it for you.

Managing Growth

A large Content Store is not necessarily a problem by itself but it can be when it begins to affect performance. Just starting the process of looking at what’s going on in the Content Store can have positive results. Our customers have real examples of bizarre behavior that can negatively impact the performance of the Content Store if it’s allowed to continue. One was a user that regularly backed up a copy of a large FM model to different locations and slowed things down to a crawl.

The adage that you can’t manage what you can’t measure really applies here. So what do you have to do here? Some of the main things are:

• Monitor growth
• Set and enforce retention policies
• Offload content that must be archived to a file server (FileNet)
• Delete orphan content
• Implement best practices for your environments
• Train users

Summary

Managing the Cognos Content Store(s) requires understanding the details of how it works and tracking its growth. With that information you can develop a plan for what’s best for your environment. Where this is done it almost always yields better operational results. For more detail on how this can be done you might want to check out the Content Store Survival Guide.

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