Data compression

The compression ratio that Content Manager OnDemand can achieve has a significant impact on the amount of space required to store reports.

The compression ratios that Content Manager OnDemand can achieve vary widely depending on the type of data and the format of the data. You cannot always accurately estimate the compression ratio by simply examining the data. On average, you can expect to achieve between 2:1 and 15:1 compression for AFP documents and up to 30:1 compression for line data reports. Compression for AFP documents is based on the output data file produced by the indexer, and not the input file, which could have been line data. When the indexer formats line data with a page definition, it may increase the size of the data by adding AFP controls for positioning text.

To properly estimate the amount of storage space required by a report, we recommend that you measure the compression ratio achieved by actually storing a sample of the report. You can store a report by using the ADDRPTOND command. The ADDRPTOND command will place entrees in the system log, which will provide before and after size values that can be used to calculate the actual compression ratio achieved.

See the IBM® Content Manager OnDemand for i: Common Server Administration Guide for more information about the ADDRPTOND command.