Hi!
Thanks for the reply!
I'm really trying to fully understand this. Taking a slightly-modified
version of your example IOCP lines below, you're saying that it's the CUNUMBR=
value that ties the CTLUNIT and IODEVICE lines together within the IOCP, but
the DS8000 doesn't care about that. The RedBooks state that the CUADD must
match the LCU ID, therefore if the CUADD=A0, then -id A0 must be specified on
the mklcu command on the DS8000:
CNTLUNIT CUNUMBR=1234,PATH=(xx,xx),UNIT=2105,
UNITADD=((00,256)),CUADD=A0
IODEVICE ADDRESS=(E000,256),CUNUMBR=1234,UNIT=3390
So if I understand you correctly, you're saying that from the z/OS side, the
-ss parameter is irrelevant, so that my mklcu should look like this:
mklcu -qty 1 -id A0 -ss A000 -lcutype 3990-6
And then I would define volumes as:
mkckdvol -extpool P0 -cap 3339 -name CKD_P0_#h A000-A0B9
And so on the DS8000, for example, I'll have volume A000, but z/OS will see
it as E000, due to the IODEVICE line??
Thank you again for taking the time to work through this with me. This isn't
something that comes up all the time and it's been fun to work through!
-Ben
________________________________________
From: IBM Mainframe Discussion List [[email protected]] on behalf of
Malcolm Beattie [[email protected]]
Sent: Saturday, March 12, 2016 5:23 AM
To: [email protected]
Subject: Re: DS8000 LCU/Subsystem
Benjamin Huntsman writes:
> I'm trying to provision a new LCU and some volumes on a DS8000. First,
> the LCU:
>
> mklcu -qty 1 -id A0 -ss E000 -lcutype 3990-6
>
> That works, and I can see the LCU. Now the volumes:
>
> mkckdvol -extpool P0 -cap 3339 -name CKD_P0_#h E000-E0B9
>
> Then, I get a load of errors, like this:
>
> CMUN02282e mkckdvol: E000: Unable to create CKD logical volume: CKD volumes
> require a CKD logical subsystem
I think it's that the volume IDs E000-E0B9 you're creating need to
have the first two hex digits matching the LCU id which in your case
is A0 (from the "mklcu ... -id A0"). The "-ss E000" isn't really
related to the important naming and mapping between I/O on the z
side and on the DS8k side. The subsystem id is just an admin-chosen
number that the DS8k will present to the operating system when it
asks. So what you probably want is:
mkckdvol -extpool P0 -cap 3339 -name CKD_P0_#h A000-A0B9
(provided that P0 is a CKD extent pool in the first place).
What the DS8k sees from the channel when the z side asks to do
I/O to a volume is the LCU id and the number of the volume within
that range (00-B9 in your example above).
Looking at the I/O from the operating system on the z side, you're
referring to a volume by its device number (ok, it's really the
subchannel corresponding to it but ignore that here). The mapping
from z device number to the (LCU id, index-within-range-on-that-LCU)
pair is done by the z channel subsystem by using what you have in
your IOCDS.
>From your mkckdvol command, I'm guessing you want those device
numbers to appear as E000-E0B9 on the z side. The relevant parts of
that here may well be something based on IOCP source (or a
corresponding HCD-created configuration) like:
CNTLUNIT CUNUMBR=1234,PATH=(xx,xx),UNIT=2105,
UNITADD=((00,256)),CUADD=1A
IODEVICE ADDRESS=(E000,256),CUNUMBR=1234,UNIT=3390
The CUNUMBR is only relevant on the z side; it isn't seen by the
DS8k and need not correspond to any number on the DS8k.
(In particular, it isn't related to the logical subsystem id,
ssid, mentioned above). It's just for matching the IODEVICE range to
the CNTLUNIT statement so I've shown it as 1234 here to emphasise
that it need not be related to any of the other numbers.
On the z side, an I/O to device E077 (for example) by the
operating system gets mapped by the channel subsystem to the
pair (1A, 77) and sent down a channel to the DS8k.
(Which channel? One of the ones listed in the PATH=(xx,xx,...)
attributes for that CNTLUNIT) to the DS8k.)
The DS8k then maps that (1A,77) to what it refers to as
volume id 1A77.
--Malcolm
--
Malcolm Beattie
Linux and System z Technical Consultant, zChampion
IBM UK Systems and Technology Group
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