Which of the following three disaster recovery technologies are commonly used? (Multiple choice)

Disaster recovery (DR) solutions are commonly categorized based on the architectural layer where data replication is implemented. The three primary and most widely adopted methods are:
1. Host-based: Replication is managed by software running on the host servers, which intercepts I/O requests and sends copies to a remote site.
2. Array-based: Replication is handled by the storage system (array) itself, operating independently of the hosts and applications. This is a core feature in enterprise storage like Huawei's OceanStor series.
3. Application-based: The application (e.g., a database like Oracle or SQL Server) manages its own data replication, ensuring transactional consistency. These three layers represent the fundamental approaches to data replication for disaster recovery.

B. Disaster recovery based on the network layer: While network-based replication using specialized SAN switches or appliances exists, it is not as commonly deployed or categorized as a primary method compared to host, array, and application-based solutions.

1. Huawei HCIA-Storage V5.0 Training Material. In the chapter "Overview of Disaster Recovery," the courseware explicitly details the three common DR technologies based on the implementation layer. It states, "According to the implementation layer, DR technologies are classified into application-level, host-based, and storage-based DR technologies." (Reference: HCIA-Storage V5.0 Training Material, Section: Common DR Technologies).

2. Huawei OceanStor Dorado Data Protection Feature Guide. The documentation, when describing remote replication features like HyperReplication (an array-based technology), often provides context by comparing it with other methods. It outlines the pros and cons of application-level, host-level, and storage-level replication, establishing them as the standard categories. (Reference: Huawei OceanStor Dorado V6 6.1.0 Data Protection Feature Guide, Section: Remote Replication Principles).

3. University Courseware. Reputable computer science and IT infrastructure courses covering business continuity and disaster recovery consistently classify data replication technologies into these three main categories. For example, course materials on storage systems distinguish between replication managed by the application, the host (volume manager/OS), or the storage array. (Reference: General curriculum structure for courses on Enterprise Storage and Disaster Recovery).