Computer Associates BABWBR1151S38 Implementation Guide - Page 28

Storage Capacity Requirements ■ You can calculate the approximate required disk space at the central site by multiplying the estimated daily ASDB growth (1MB for every 100 sessions) by the number of days of database retention time. For example: If you have 10 branch sites with each site having 10 nodes and each node contains 4 volumes, then the central ASDB will grow by 4MB every day. If the database record is retained for 180 days, then the central ASDB will need to be 720MB. - 10 branch sites x 10 nodes x 4 volumes = 400 sessions - 400 sessions = 4MB database space growth per day (1MB per 100 sessions) - 4MB daily growth x 180 database retention days = 720MB total database space required for the central ASDB Note: Any database pruning that is performed at a branch ASDB will be reflected in the central ASDB the next time data synchronization is performed. Storage Capacities and Resources Your ability to meet your storage-capacity requirements depends on the following criteria: ■ The types of libraries you have ■ The number of each type you have ■ The types of media each library uses After you have identified types and numbers of libraries that will be available, you can calculate the capacity of each library using the following formula: totalcapacity = numberslotsavailable × mediaelementcapacity In this formula, the numberslotsavailable is the number of slots available in the robotic library and mediaelementcapacity is the capacity of the media elements used by the installed drives. Media Capacities The raw capacity of the media varies with the type of drives, the type of media, and the degree of data compression that you are using. You should deduct the following from the raw capacity to arrive at the real data capacity: Deduct ~10% for overhead. This allows for the CA ARCserve Backup media header and various engine-specific overhead information. Note that the overhead may be more if you are backing up a large number of very small files. 28 Implementation Guide