Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!inuxc!iuvax!pur-ee!uiucdcs!uxc.cso.uiuc.edu!uicsrd!kai From: kai@uicsrd.UUCP Newsgroups: comp.os.vms Subject: halve BACKUP times easily Message-ID: <6300002@uicsrd> Date: Mon, 6-Jul-87 21:16:00 EDT Article-I.D.: uicsrd.6300002 Posted: Mon Jul 6 21:16:00 1987 Date-Received: Sat, 11-Jul-87 10:46:56 EDT Lines: 31 Nf-ID: #N:uicsrd:6300002:000:1484 Nf-From: uicsrd.CSRD.UIUC.EDU!kai Jul 6 20:16:00 1987 There was a item in this months DEC Professional Magazine that should be of interest to VMS system managers and operators. Using the following VMS/BACKUP switches can HALVE your cpu and elapsed time. I tried this on a one of my VAX 750's Massbus disks (approx. 65 Mb) to a CDC 92185 tape drive at 6250 bpi, and cut the full disk backup elapsed time from 35 minutes to 17 minutes (on an unloaded system) and cputime used from 10 minutes to 5 minutes. BACKUP/IMAGE/NOCRC/BUFFERS:5/BLOCKSIZE:16384 dra2: msa0:dra2.bck The idea behind this is that BACKUP was written a long time ago, when 6250 bpi tape drives were non-existent or very expensive. 1600 bpi tape drives do not have the hardware built in for performing CRC checking of the data, however 6250 bpi tape drives DO. So why have your VAX waste it's time doing double CRC checking? The /BUFFERS and /BLOCKSIZE switches help, and should probably be used even if you don't want to trust the /NOCRC switch. I compared this to our Raxco Rabbit-5 fast backup program (which I normally use), and Rabbit-5 took 15 minutes to backup the same disk. Hardly worth the $4000 price tag just to have a barely functional tape library manager (and vaporware file locator). Patrick Wolfe internet: pwolfe@kai.com Kuck & Associates, Inc. uucp: {seismo,ihnp4,uiucuxc}!kailand!pwolfe 1808 Woodfield Dr. bitnet: pwolfe%kailand@uiucuxc Savoy, IL 61874 csnet: pwolfe%kailand%uxc@uiuc.csnet