Thank you everyone ...I understand it now ...Thanks a lot ! Linda
On Tue, Jun 14, 2016 at 5:39 AM, Alan Altmark <alan_altm...@us.ibm.com> wrote: > On Fri, 10 Jun 2016 16:53:42 +0530, linda golding < > lindagolding...@gmail.com> wrote: > >Does anyone know how OSA-ICC devices (3270-X) are mapped in HSA ? > > > >I did a search in our systems and see that OSA-ICC devices are > concurrently > >active on all LPARS of the sysplex . I also see that PCHID is same across > >all the systems . I am just trying to find out how multiple systems can > >write on to the same physical OSA-ICC device ?..Basically i would like to > >know how this happens at hardware level . Any pointers /documentation > would > >be a great help . > > It works because of the magic of the Multiple Image Facility, MIF. Device > numbers are for the wetware. The host OS doesn't use them, but instead > uses a subchannel number, for which there is a 1-1 binding with a device > number in the LPAR. (The STORE SUBCHANNEL instruction provides the binding > information.) > > For every device (UA) in the I/O config, IOCP creates a subchannel for > each LPAR in the access list for the device. The metadata for the > subchannel includes the owning LPAR's CSS and MIF ID. When the LPAR uses > one of its subchannels to communicate with a device, the channel subsystem > grabs the UA, CSS and MIF ID, and sends them with the I/O request to the > CU. That means that two LPARs can use the same UA on the same CU, and the > CU can tell them apart. (Yay!) Recognizing the CSS and MIF ID is what > makes a device MIF-capable. > > Now, the extent to which a CU surfaces this knowledge to the management > interfaces varies. OSA-ICC makes it very visible. You associate a > TN3270E LUNAME with a particular CSS, MIF, and, optionally, a particular > device number. The OSA has the distinct advantage of having access to the > I/O configuration data, so it can see the device number associations and > show them to you in the configuration panels, not requiring you to do the > device number <-> UA translations yourself. > > Alan Altmark > z/VM Consultant > IBM Lab Services > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
