Intel 170 Servers, AS/400 RISC Server, 7xx Servers manual 200, Virtual Tape

15.12 Virtual Tape

Virtual tape drives are being introduced in iV5R4 so those customers can make use of the speed of saving to DASD, then save the data using DUPTAP to the tape drives reducing the backup window where the system is unavailable to users. There are a lot of pieces to consider in setting up and using Virtual tape drives. The block size must match the physical backup device block capabilities you will be using. The following helps to show that even if your workload is large file you may not gain anything in your back up window even using the virtual tape drives. If your tape drive uses smaller block sizes your virtual tape drive must use small blocks

VRT32K vs VRT256K Block size 570 16 way 128GB Memory

800 DASD units for Virtual Tape Drives

	1600
	1400	VRT32K Large File
	1200
		Save
	1000	VRT256K Large File
		Save
GB/HR	800	VRT32K Large File
	600
		Restore
		VRT256K Large File
	400	Restore
	200
	0	1 Virtual Tape Device
		Operation

IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
© Copyright IBM Corp. 2008	Chapter 15. Save/Restore Performance	255