Thanks Alan. The device is supported 'DASD'. I'll open a PMR. For now it is just an annoyance. I get the message for each PATH to the device, but none of them ever go offline.
On Wed, Aug 18, 2010 at 3:03 PM, Alan Altmark <alan_altm...@us.ibm.com>wrote: > On Wednesday, 08/18/2010 at 04:48 EDT, Tom Huegel <tehue...@gmail.com> > wrote: > > What is a path group id? Where do I find it. > > I see this message everytime a certain user attaches or detaches a > device. > > HCPDPM1281I PATH E6 TO DEVICE 3B18 NOW OFFLINE; PATH GROUP ID MISMATCH. > > A path group id is a 'handle' that identifies a host to a control unit. > Among other housekeeping duties, it lets a disk or tape drive know whether > or not to allow an I/O operation from a particular path if there is an > outstanding RESERVE on the device. > > Bottom line, it lets the device treat all the paths to the host as a > single logical pipe. One ring to rule them all. > > Now, on to the bizarre behavior.... > > Is this a device that is defined as UNSUPPORTED? (QUERY rdev. If it says > "DASD" it is supported. If it says "DEV" it isn't.) If unsupported, is > it defined DPS YES or NO? (DPS indicates whether or not the device > supports Set Path Group ID.) > > When a DPS=YES device comes online, CP will set the path group id (PGID) > in the device UNLESS the device is defined as unsupported with DPS NO. If > you lied to CP about DPS, and then the guest comes along and sets the > PGID, that will create problems for CP since he knows the guest set the > PGID (CP is ever vigilant). CP will discover that the guest has set some > other PGID and that it doesn't match his own. HCP1281I is the result. > Setting the PGID can only be done once per IPL unless special action is > taken to reset the device, CU, or chpid. > > It isn't clear if CP should even be checking on a DPS=NO device. > > The best way to get to the bottom of this is to open a PMR. > > Alan Altmark > z/VM Development > IBM Endicott >
