In a recent note, Edward Jaffe said: > Date: Wed, 2 Aug 2006 12:58:12 -0700 > Reply-To: IBM Mainframe Discussion List <[email protected]> > Sender: IBM Mainframe Discussion List <[email protected]> > From: Edward Jaffe <[EMAIL PROTECTED]> > Organization: Phoenix Software International, Inc. > Subject: Re: Data set ENQueues and DEQueues in Jobs > In-Reply-To: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Patrick O'Keefe wrote: > > Ok, that will give 2 different devices with the same volser, but you > > won't get 2 different volsers for the same device. In the case of ENQ/DEQ > > you won't an ENQued device accessable by another name. I *think* that > > was the context of the statement, but I may be wrong. > > While it isn't possible to have two different volsers for the same > *physical* device, you can /easily/ have two different volsers for the > same device number (which is all MVS knows)! Suppose you have a DASD > subsystem attached as '80xx' on system "A". You could attach that same > subsystem as '90xx'on system "B"! > When two different entities are known by the same name, there's no integrity hazard; merely an unnecessary restriction of availability because of a superfluous ENQ, as happens today when a systems programmer wants to build a copy of SYS1.LINKLIB for testing (and then delete it).
If one entity is known by two different names, there is an integrity hazard, because two systems may obtain EXCL ENQ of it by the different names and unwittingly update it concurrently. Are you sure that a single volume can't be known by two different names? Consider: surely it's possible to rename a volume (the verb "clip" comes to mind). Can one system dismount and rename a volume while it remains mounted on another system, then remount it by the new name while the other system still knows it by the old name? -- gil -- StorageTek INFORMATION made POWERFUL ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
