Don,

Did the person suggesting that you eliminate the "disk owner" userid give 
a reason why it was better and to justify the effort?

One possibility that it could be better with a "disk owner" userid is that 
by doing so, one can use an External Security Manager (ESM) such as 
VM:Secure or RACF/VM to limit the access to the disks from a single place.

Regardless of which method you choose, you can (we do) include all the 
z/OS guest "common" directory statements and shared mdisks in one place 
using a directory profile, e.g. 

DIRECTORY ...
...
PROFILE xxxxPROF 
 ACCOUNT OVERHEAD 93S0 
 MACH ESA 64 
 IPL CMS PARM AUTOCR 
 OPTION CFUSER 
 OPTION COMSRV 
 OPTION DEVINFO 
 OPTION DEVMAINT 
*OPTION DIAG98 !! NOT FOR z/OS vm's - causes OSA and TCPIP errors !! 
 OPTION MAINTCCW 
 OPTION MAXCONN 65535 
 OPTION MAXVMCFI 2147483647 
 OPTION MIH 
 OPTION NOMDCFS 
 OPTION QUICKDSP 
 OPTION RMCHINFO 
 OPTION STGEXEMPT 
 OPTION SVC76VM 
 OPTION TODENABLE 
 OPTION SVMSTAT 
*OPTION V=F 
*OPTION V=R 
*XCONFIG ACCESSLIST ALSIZE alecount 
*XCONFIG ADDRSPACE MAXNUMBER nnnnn TOTSIZE nnnnG SHARE|NOSHARE 
*XSTORE ALL|size 
 LINK MAINT 190 190 RR 
 LINK MAINT 19D 19D RR 
 LINK MAINT 19E 19E RR 
 SPECIAL 701 3270 
 SPECIAL 702 3270
...
* 
 SPECIAL 0100 MSGPROC CF1 
 SPECIAL 0200 MSGPROC CF2 
* 
 LINK xxxxDASD 5500 5500 MW 
 LINK xxxxDASD 5501 5501 MW 
 LINK xxxxDASD 5502 5502 MW 
...
USER xxxxDASD   NOLOG            (as you can see, we have a "disk owner" 
ID, too) 
 MDISK 5500 3390 DEVNO 5500 RV READ WRITE MULT 
 MDISK 5501 3390 DEVNO 5501 RV READ WRITE MULT 
 MDISK 5502 3390 DEVNO 5502 RV READ WRITE MULT 
...
USER xxx1    xxxxxxxx    4G 16E   GB 64 
* See above: PROFILE xxxxPROF for common xxxn statements 
 INCLUDE xxxxPROF 
 SHARE RELATIVE 250 
 ACCOUNT xxx1   wherever 
...

Using a directory profile keeps things in one place so that all the guests 
are changed at one time in one place - leaving fewer moving parts to keep 
in synch.

Ultimately, it comes down on which way you want to skin the furry critter 
of your choice.

Mike Walter
Hewitt Associates
The opinions expressed herein are mine alone, not my employer's.




"Don" <[EMAIL PROTECTED]> 

Sent by: "VM/ESA and z/VM Discussions" <[email protected]>
01/31/2006 11:51 AM
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Subject
MDISK versus LINK






I have a situation where multiple z/OS guests need to share DASD. In the
past I have used a userid as a disk holder with MDISKs using DEVNO and 
MWV.
The guests would then LINK to the MDISKs using MW. It has been suggested
that I eliminate the disk holder userid and use MDISK statements only. 
Each
guest would then have an MDISK for the same address. For example, 
MDISK D000 3390 DEVNO D000 MWV

Does anyone know if there is any advantage or disadvantage to one way over
the other?




 
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