HP B6960-90078 manual Example, 234

Backup

Using Backup Options

• Objects that reside on the client connected to the backup device have

	a higher priority.
	• Objects are selected so that the number of Disk Agents per client is
	kept as low as possible.
	The size of objects does not play a role in assigning an object to a device.
	If a device becomes unavailable, the following happens:
	• All objects backed up to the device before the failure time are actually
	backed up.
	• All objects that are being backed up to the device at failure time are
	aborted.
	• All objects pending to be backed up to the device will be backed up to
	some other available device specified in the backup specification, if
	the maximum number of devices has not been used.
Example	For example, assume that there are 100 objects configured for backup to
	four devices with concurrency set to three and with load balancing
	parameters MIN and MAX both configured at two. If at least two devices
	are available, the session will start with three objects being backed up in
	parallel to each of the first two available devices. The other 94 objects
	will be pending and will not be assigned to a particular device at that
	time.
	Once a backup of a particular object is done, the next pending object is
	started and assigned to the device that has less than three concurrent
	objects being backed up. Load balancing ensures that the two devices are
	running in parallel as long as there are still pending objects to be backed
	up. If a device fails during backup, one of the two devices in reserve is
	used. The objects that were being backed up to the failed device are
	aborted, while the next three pending objects are assigned to the new
	device. This means that each failure of a device can cause a maximum of
	three objects to be aborted, provided that other devices are available for
	the backup session to continue.
	The following rules should be considered when applying device options
	from a template:
	• If the load balancing option is not selected in the template, the device
	options are not used with the backup specification.
	• If the load balancing option is selected in both the template and the
	backup specification, the device options are applied.

234 Chapter 5