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Re: How to define the system disk logical to another one

 
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Song_Charles
Frequent Advisor

How to define the system disk logical to another one

I have a question,
Could I define the system disk logical name to another one?
For example, after installation,the default logical name define to sys$sysdevice, could I add another logical name to system disk, such as "DRA0"?

B/R
Charles Song
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18 REPLIES 18
David B Sneddon
Honored Contributor
Solution

Re: How to define the system disk logical to another one

Charles,

You can define as many logicals as you wish to
point to the system disk (or any other disk).
Is this because of hard coded logicals in your
application?
Assuming that DRA0 is not a valid device on the
system then doing

$ define/system dra0 sys$sysdevice:

should work. You may also want to add /EXEC.

Dave
Song_Charles
Frequent Advisor

Re: How to define the system disk logical to another one

Thank you,
I try and successfully.
Charles
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Mobeen_1
Esteemed Contributor

Re: How to define the system disk logical to another one

Charles

Define/sys/exe dra0 sys$sysdevice:

should do the trick

By any chance if you do a mistake and need to delete the logical, then use the following

deassign/sys/exe sys$sysdevice

regards
Mobeen
Antoniov.
Honored Contributor

Re: How to define the system disk logical to another one

Hi Charles,
using define you can make a little joined filesystem, for example:
$ DEFINE/SYSTEM DRA0 DKA0:,DKA100:
in prior example every file accessed in DRA0 is searched in DKA0 and then in DKA100

Antonio Vigliotti
Antonio Maria Vigliotti
Willem Grooters
Honored Contributor

Re: How to define the system disk logical to another one

Mobeen


deassign/sys/exe sys$sysdevice


I wouldn't do that, for this, or any other SYS$-logical.
All these logicals are setup within the startup procedure, and I believe that quite some software relies on the existence of these logicals - and a proper definition.

There is not any proplem to make another logical (whatever one) referring to the very same device.

Willem
Willem Grooters
OpenVMS Developer & System Manager
Uwe Zessin
Honored Contributor

Re: How to define the system disk logical to another one

Mobeen,

I don't think your advice is correct. With the 'define' command you create a logical name 'DRA0' in the system table with the equivalence name of 'SYS$SYSDEVICE:'. It will be the logical name translation services that first translate 'DRA0', find 'SYS$SYSDEVICE' and then translate this name unless you create a logical name with the /TRANSLATION_ATTRIBUTES=TERMINAL.

If you put a wrong equivalence string into 'DRA0', then you need to deassign this name! Or just do a new DEFINE command overwriting the previous assignment. You must not deassign the eqivalence string!!

You are lucky here, because the system will not have a logical name "SYS$SYSDEVICE:" (note the colon at the end):
$ deassign /system /executive_mode sys$sysdevice:
%SYSTEM-F-NOLOGNAM, no logical name match
$
.
Jan van den Ende
Honored Contributor

Re: How to define the system disk logical to another one

Charles,

like Willem wrote, you can define (nearly) as many logicals as you want, BUT (as David implied, but I want to stress that strongly):

Do NOT define a logical name that is also the device-name of ANY device in your system/cluster!

Willem already warned you NOT to deassign any SYS$ logical.
I would add to also NOT re-define any, unless you are VERY sure of what you are doing, and then, first do a VERY thorough testing on a system that is NOT important if it still has more consequences than you expect!

In short: SYS$ logicals are the heart of VMS, and tampering with them is like performing open-heart surgery. Leave it to specialised surgeons, or become one yourself.

Jan
Don't rust yours pelled jacker to fine doll missed aches.
Anton van Ruitenbeek
Trusted Contributor

Re: How to define the system disk logical to another one

Charles,

I understand the question but I think you mean: How can I define another logical to the systemdisk ?
The logical SYS$SYSDEVICE cannot be moved.

AvR
NL: Meten is weten, maar je moet weten hoe te meten! - UK: Measuremets is knowledge, but you need to know how to measure !
John Eerenberg
Valued Contributor

Re: How to define the system disk logical to another one

Hi Charles,

Redefing sys$sysdevice is, as most have said, not a great idea.

Digital's naming convention is that the "$" is reserved to VMS. The "_" is reserved for us as system managers and in this case we can use it in place of the "$". So how about a
$ define/sys/exe sys_sysdevice "$1$dga101:,$1$dga102:,..."
?

The names are very similar so that is a draw back but it does adhere to naming standards for VMS.

Maybe that helps.

john
It is better to STQ then LDQ