How the Agent Works
Chapter 1: Introducing the Agent 13
How the Agent Works
CA ARCserve Backup and the agent work together to back up and restore SQL
Server databases. When CA ARCserve Backup backs up a database, it sends a
request to the agent. The agent retrieves a point-in-time-consistent image of the
database or its transaction log from Microsoft SQL Server in the form of a logical
data stream, and sends it to CA ARCserve Backup, where the complete database
image is backed up to media. During a restore, the agent functions in a similar
fashion, and transfers the backed up database from CA ARCserve Backup to
Microsoft SQL Server.
The agent takes advantage of the Microsoft SQL Server dump database and
transaction log backup method. A dump backs up the database or transaction log
in a single step. This ensures that a consistent image of the database is backed
up.
For each database or transaction log submitted for backup, the agent initiates a
dump in Microsoft SQL Server. Microsoft SQL Server sends the database to the
agent in a series of data chunks. The agent receives the data, one chunk at a
time, and passes it directly to CA ARCserve Backup, where it is recorded to
backup media.
In a restore operation, for each database or transaction log backup being
restored, the agent initiates a load operation in Microsoft SQL Server, and then
returns the backed-up data to Microsoft SQL Server in the same manner that the
data was provided during backup. If a single database requires more than one
backup to restore it, CA ARCserve Backup assists in assembling the correct
sequence of restore operations to be able to fully restore the database.
How a Backup Request Works
Backup jobs use the following process:
1.
You start a backup job in CA ARCserve Backup.
2.
CA ARCserve Backup sends the request to the agent for a database.
3.
The agent retrieves a particular database or transaction log from Microsoft
SQL Server, which sends multiple data chunks to the agent.
4.
The agent retrieves the data chunks and transfers them to CA ARCserve
Backup, which backs up the data to the specified storage media.
