Thank you John and Curtis for the explanation .
Infact , I should have said UCW instead of UCB to make it more clear . But now i understand that they could be physically different devices . On Wed, Jun 8, 2016 at 2:09 AM, Pew, Curtis G <[email protected]> wrote: > 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 > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
