Storage requirements overview

To estimate storage requirements for a Content Manager OnDemand system, you must understand and document user requirements for storing and accessing data.

Reports and other data provides information that can help you gather user requirements.

Before you turn requirements into a storage subsystem to support your system, you must also review the various operational and performance issues. For example, Content Manager OnDemand supports up to 128 index fields for each report. However, users typically do not need many indexes to locate a specific version of a report or a document within a report. The number of index fields that you define has a direct impact on the amount of disk space that you need for your database.

In addition, the more indexes that you define for a report, the more time is required to load the report into the system. You must work with users and understand their data retrieval requirements. Define only the number of index fields that they need. You might have to balance user requirements with disk space, the amount of time required to load a report, and other performance issues.

Maintaining a copy of reports in cache storage can significantly impact the amount of disk storage that you need on your system. Most customers store the latest versions or most frequently accessed reports in cache storage. You should review how users search for and retrieve information from the reports that you plan to store in Content Manager OnDemand. For example, if most retrievals occur in the first 90 days after a report is generated, then you probably want to store the report in cache storage for at least that length of time. You should choose a time to cache each report that meets the requirements of your users and also makes the best use of available cache storage space.

You need several components to measure to determine the amount of disk, optical, and tape storage required to support a Content Manager OnDemand system. For example, the following components of the system require disk storage: The following components of the system require archive storage (optionally VSAM files or OAM objects):

When you calculate archive storage requirements, you should also determine the number of storage volumes and libraries that you need to support the data that will be stored on your system. Optical libraries are capable of holding a large amount of data, with the storage capacity usually expressed in amounts of uncompressed data.

Depending on the compression ratio achieved for your reports, an optical library might be able to hold more than the stated amount. For example, if Content Manager OnDemand can achieve a 6:1 compression ratio on the reports that will be stored in an IBM® 3995 optical library, the library can hold multiple terabytes of report data, depending on hardware configuration.

You can replace full optical storage volumes as needed, if the availability requirements of your system allow you to do so. For example, you might decide to remove full storage volumes from a library one year after the last time that Content Manager OnDemand wrote report data to the storage volume. You could replace the full storage volumes with newly initialized storage volumes to hold the latest reports stored on the system. That way, the latest versions of a report are always available in the library. However, if you need to keep many years of report data online in the library or you store massive amounts of data in your application groups, then you might need to plan on having several optical libraries for your system.