HP StorageWorks Application Recovery Manager Administrator's Guide (T4395-96004, February 2008)

Introduction
Concepts
Chapter 18
• coordinating restore session start
• requesting the instant recovery
Backup
During the Application Recovery Manager backup, Application Recovery
Manager does not interact directly with each writer, but through the VSS
interface. It uses the VSSBAR agent to coordinate the backup process.
The consistency of data is a responsibility of the VSS writer and not
dependent on Application Recovery Manager functionality. The backup
process of the VSS writers consists of the following phases:
1. When you select writers and components you want to back up and
start a backup, Application Recovery Manager communicates with
the Volume Shadow Copy Service (backup coordinator) to notify that
the backup is about to start.
2. The coordinator identifies all supported writers and passes the list of
available writers and their characteristics (Writer Metadata
Document) back to Application Recovery Manager.
3. Application Recovery Manager examines Writer Metadata and
identifies the volumes that contain the data to be backed up. Then the
VSS informs available writers about selected components.
4. Application Recovery Manager prepares a list of volumes (shadow
copy set) that must be put into consistent state, and passes the list
back to the coordinator for preparing a shadow copy.
5. The VSSBAR agent notifies the writers about the shadow copy
creation. The VSS mechanism ensures that there are no writes on the
volume while the shadow copy is being created.
6. When the writers are fully prepared for the consistent shadow copy
backup, the VSSBAR agent passes shadow copy creation requests to
VSS.
7. After the shadow copy set is created, the VSSBAR agent coordinates
the VDS agent to gather information on the created replica that is
needed for instant recovery.