ANK@CUNYVMS1.BITNET (ANIL KHULLAR) (01/11/88)
I was wondering if it is possible to somehow use BACKUP over DECNET ?
We have a uVAX II connected to an 11/780 and uVAX II users want to be
able to BACKUP to our TU and TS tape drives. They currently have to unpack
the files on VAX 11/780, and copy it over network. I remember a few months
ago a discussion on the similar issue, but somehow i cannot find the
old mail files.
We have a MicroVMS 4.5 on uVAX II and VMS4.4 on VAX 11/780
Anil Khullar
{Ph.D. Prog in Psychology
C.U.N.Y. Grad. Center.
33 W 42 St. Box 295,
New York NY 10036 }
BITNET:ank@cunyvms1
INTERNET:ank%cunyvms1.BITNET@cunyvm.cuny.edu
:ankgc@cunyvm.cuny.edu
==========================================================================nagy%warner.hepnet@LBL.GOV (Frank J. Nagy, VAX Wizard & Guru) (01/12/88)
The problem is that tape drives cannot be directly accessed across
the network because there is no way to request a tape mount. However,
use DECnet task-to-task communcations and some command procedures,
a workaround is possible.
Let us assume the backups are going to be done under account
BACKUPABUSER (account exists on both systems and has proxy logins).
On NODEA, the following procedure is stored in the login area
of BACKUPABUSER. This procedure will be invoked as a DECnet object
from NODEB (see below). The procedure is:
$ ALLOCATE MSA0:
$ INITIALIZE /DENSITY=1600 MSA0: BACKUP
$ MOUNT /BLOCK=4096 MSA0:
$ ON ERROR THEN $ GOTO FINISH
$ CONVERT /FDL=SYS$INPUT SYS$NET: MSA0:BACKUP.BCK
RECORD
FORMAT FIXED
SIZE 4096
$!
$FINISH:
$ DISMOUNT MSA0:
$ DEALLOCATE MSA0:
$ EXIT
Mount a tape on the drive, login into BACKUPABUSER on NODEB and type the
command:
$ BACKUP [*...] NODEA::"TASK=BACKUPS"/SAVE_SET/BLOCK=4096
and the [BACKUPABUSER...] directory tree will be saved across the network.
This can be obviously extended to doing full disk saves, incrementals,
etc. from privileged accounts. The command procedure can be installed
as a DECnet object (using NCP) so that the command procedure does
not have to be in the login area of a proxy account, etc. etc.
You might be able to use a larger tape block size by replacing all
the "4096" by another value like "8192" or whatever.
What you lose with this is (1) performance will not be as good as
direct tape writing by BACKUP and (2) you lose BACKUP's more sophisticated
handling of tape errors.
This information was extracted from an article on pages 25-26 of the
October 20, 1986 issue of Digital News. If you can hunt up a copy, you
can find a more detailed explanation.
= Frank J. Nagy "VAX Guru & Wizard"
= Fermilab Research Division EED/Controls
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