HP B6960-90078 manual Hardware Compression, Full and Incremental Backups

	Further Information
	Performance Considerations
NOTE	By default, software compression should be disabled. Software
	compression should only be used for backup of many systems over a slow
	network where the data can be compressed before sending it over the
	network. If software compression is used, hardware compression should
	be disabled since trying to compress data twice actually expands the
	data.
	Hardware Compression
	Hardware compression is done by a device, which receives the original
	data from the Media Agent client and writes it to the tape in compressed
	mode. Hardware compression increases the speed at which a tape drive
	can receive data, because less data is written to the tape.
	By default, hardware compression should be enabled. On HP-UX and
	Solaris, hardware compression should be enabled by selecting a
	hardware compression device file. On Windows NT and Windows 2000,
	hardware compression can be selected during the device configuration.
	Using hardware compression or not should be a conscious decision,
	because media written in compressed mode cannot be read using the
	device in uncompressed mode and vice-versa.
Limitations	HP Ultrium LTO drives use automatic hardware compression which
	cannot be disabled. Ensure that you do not enable Software
	compression when you configure an HP Ultrium LTO drive.
	Full and Incremental Backups
	A basic approach to improve performance is to reduce the amount of
	backed-up data. Take full advantage of time and resources when
	planning your full and incremental backups. An important consideration
	is that there is no need to do full backups of all the systems on the same
	day, unless necessary. See the HP OpenView Storage Data Protector
	Concepts Guide for more information.

Appendix A A-11