On Jun 7, 2016, at 3:08 PM, baby eklavya <[email protected]> wrote: > > To my understanding , when sharing MCS consoles in a sysplex , one thing > which matters is the console name which has to be unique for each LPAR even > though the UCB can be the same . Then again , console uses EXCP to write > the screen of data each time . Since the UCB is shared , how does it > actually work ? > > Unlike DASD devices which goes via SSCH logic in which the device busy > status is checked when applications from multiple LPARS try to write on the > same UCB ,the console seems to be working in a different way in a sysplex . > > I have been searching on this for a while , but couldn't find anything > documented about this so far . Can someone clarify /guide me where i can > find this information ?
I think you’re confused. UCB’s are not shared between LPARs; a UCB is a control block (that’s the ‘CB’ part of ‘UCB’) managed by MVS within the LPAR’s storage, so it can’t be shared. If you’re talking about OSA-ICC consoles, then the physical port can be shared between LPARs, and two LPARs can have the same device numbers sharing that port, but they are still unique logical devices and have different TN3270 LU names. In the OSA configuration you map TN3270 LU names to unique LPAR/device number pairs. Here’s an extract from on of the OSA configurations on my system: <CONFIG_SESSION> <SESSION1> CSS= 00 IID= 01 DEVICE= 0200 GROUP= "PC200" CONSOLE_TYPE= 2 RESPONSE= OFF READ_TIMEOUT= 60 </SESSION1> … <SESSION17> CSS= 00 IID= 02 DEVICE= 0200 GROUP= "T1C200" CONSOLE_TYPE= 2 RESPONSE= OFF READ_TIMEOUT= 60 </SESSION17> If I configure my tn3270 client to connect to LU “PC200” it will connect to device number 200 on the LPAR with id 01, while if I configure it for LU “T2C200” it will connect to device number 200 on the LPAR with id 02. The only thing being shared here is the physical port (and its IP address) and, on the other end, the device number. But they are two distinct logical devices, and each has its own UCB managed by the instance of z/OS in the appropriate LPAR. (I guess another thing that might be confusing about this is that if you look at HCD you’ll only see one device with device number 200, apparently “shared” by the LPARs. But all that’s really being shared is the physical port and the device number.) -- Pew, Curtis G [email protected] ITS Systems/Core/Administrative Services ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
