Chapter 8 Quality attributes and sizing of the dXp Availability Requirements Availability provides the uptime availability of the system. Maximum availability is necessary to ensure high-quality service for the end users. • The system should provide maximum and continuous availability. In order to provide preferred 99.999% availability, the system downtime should be a maximum of 5.26 minutes per year. • Even during peak traffic, the system’s availability should not be impacted. • The availability of the system should be ensured even when one of the back-end systems or services is down. • The data, code, and content should be synched up on a regular basis to a disaster recovery (DR) site to handle unexpected disasters and ensure business continuity. • In case of unexpected disasters, the DR site should be up and running within the recovery time objective. • The recovery time objective (RTO) (the maximum time period within which the DR site should be made active during disasters) should be designed based on availability SLAs. In order to provide 99.999% availability, we should have an active DR site that can take over immediately after the primary site is down. • The recovery point object (RPO) (maximum period for which data loss is tolerated) should be designed based on availability SLAs. In order to provide 99.999% availability, we should have an active DR site to which we do a real-time data sync. • The system should be available during upgrades and patching process. 220