VSS SQL and Exchange Implementation Diagrams

Two scenarios are provided to illustrate the use of shadow copies in a backup operation; one scenario includes a remote replication.

Scenario 1

  1. Virtual disks have been served to the Production SQL and Exchange Servers and are being used as storage resources.
  2. I/O requests are sent from the Production SQL and Exchange Servers to the Preferred Server where they are processed and data changes are mirrored to the Alternate Server.
  3. VSSclients, Production SQL and Exchange Servers, each issue a series of DiskShadow commands to create shadow copies of the application data files, and transport the metadata files to the Backup Server:
    • Initial commands to prepare for shadow copy creation are executed such as Set MetaData, Set Option, Set Context.
    • Volumes containing data files are added to the shadow copy set.
    • The backup session begins.
    • The command to create shadow copies is issued. VSS quiesces the production server and flushes the data to disk. When quiesced, the snapshots are created on the active server and the production server resumes I/O processing. In this case, the active server is the alternate server.
    • The backup session is ended.
    • The metadata file is transported to the Backup Server which will receive the backup shadow copies.
  4. The VSS client, Backup Server, issues a series of DiskShadow commands to receive the metadata files and shadow copies that were created on each production server:
    • Initial commands to prepare to receive the backup shadow copies such as Load MetaData.
    • Import the shadow copies.
    • Expose the shadow copies.
    • The backup shadow copies have been successfully transferred to the Backup Server.

Scenario 2

  1. Virtual disks have been served to the Production SQL and Exchange Servers and are being used as storage resources. Replications have been configured between the Alternate Server as the replication source and the Remote Server as the replication destination.
  2. I/O requests are sent from the Production SQL and Exchange Servers to the Preferred DataCore Server where they are processed and data changes are mirrored to the Alternate Server.
  3. VSS clients, Production SQL and Exchange Servers, each issue a series of DiskShadow commands to create shadow copies of the application data files:
    • Initial commands to prepare for shadow copy creation are executed such as Set MetaData, Set Option, Set Context.
    • Volumes containing data files are added to the shadow copy set.
    • The backup session begins.
    • The command to create shadow copies is issued. Once the VSS quiesces the production server and flushes the data to disk, the snapshots are created on the active server and checkpoint markers are sent from the Alternate Server (Replication Source) to the Remote DataCore Server (Replication Destination). When complete, the production server resumes I/O processing.
    • The backup session is ended.
    • If the shadow copy source is the source of a replication, a checkpoint marker will be sent to the replication destination to update the assigned checkpoint snapshot. The snapshot to update should be pre-configured on the destination server in order to act upon it. (The snapshot created on the replication destination is not part of the shadow copy.) Once the checkpoint markers are received at the destination, snapshots of the database files are updated on the Remote Server.
    • The snapshots can be served to the Backup Server.