When a back up process is initiated, significant n/w communication takes place between the different components of a backup infrastructure.

The backup operation is typically initiated by a backup server,but it can also be initiated by a backup client.

The backup server initiates the backup process for different backup clients based on the backup schedule configured for them.For e.g. backup process for a group of backup clients may be scheduled to start 2:00 am everyday in the morning.

The backup server coordinates the backup process with all the components in a backup environment.

The backup server maintains the information about backup clients to be backed up and storage arrays to be used in a backup operation..

The backup server retrieves the backup-related information from the backup catalogue and, based on this information, it instructs the storage array to load the appropriate backup media into backup devices. Simultaneously, it instructs the backup clients to gather the data which is required to be backed up and send it over the network to the assigned storage array.

After the backup data is sent to the storage array, the client sends some backup metadata(i.e, the number of files,name of the files,storage array details,etc) to the backup server.

The storage array receives the backup clients data, organises it and sends it to the backup devices.

The storage array then sends the additional backup metadata(i.e, location of the data on the backup device,time of backup,etc) to the backup server.

The backup server updates the backup catalogue with this entire information.

Following are the steps for backup operations(see figure above)

1. Backup server will initiate the schedule of the backup process.

2. Backup server will retrieve the backup-related information from the backup catalogue.

3a. Backup server will instruct the storage array to load backup media in the backup device.

3b. Backup server will instruct backup clients to send the data which has to be backed up to the storage array.

4. Backup clients then send the data to the storage array and also update the backup catalogue on the backup server.

5. Storage array then sends the data to the backup device.

6. Storage array then sends the metadata and media information to the backup server.

7. Finally, the backup server will update the backup catalogue.