🚀 go-pugleaf

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