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DevOps Tricks: How to Migrate From a z/OS System to zD&T

migrate-zD&T

DevOps—or development operations—is an approach to continuous software delivery through automation and collaboration. IBM z Systems Development and Test environment (zD&T) simplifies infrastructure requirements for mainframe development and testing by providing an identical mainframe-like environment that runs on Linux in x86 architecture. It’s possible to migrate z/OS from a host mainframe to zD&T or use Application Developers Controlled Distributions (ADCD) with zD&T. In this article, we will discuss how we migrated a z/OS system from host mainframe to zD&T.

The high-level steps in migrating a z/OS system to zD&T are:

  • Device map customization
  • Network customization between Linux and zD&T
  • Moving DASD volumes to zD&T

The z/OS system that we migrated from the host mainframe is a small monoplex. It’s spread over five mod-9 DASD volumes, one of which is SMS managed, and has a CICS region and a DB2 subsystem. In this article, we will refer to this system as the “host z/OS system,” or the “host z/OS.” The host z/OS system after migration to zD&T will be referred to as the “zD&T z/OS system,” or “zD&T z/OS.” When we had to make changes to PARMLIBs, VTAMLST or any other PARMS, we did so in the host z/OS system before moving the DASD volumes to zD&T.

Device Map Customization

A device map (devmap) is a text file used by zD&T to define devices and resources like RAM and CPU, available to z/OS that will be run. A devmap is similar to the Input Output Control Program input file, which can be used to build Input Output Configuration Data Sets for Power-on Reset of the mainframe. However, devmap has other details like RAM and CPU (including specialty engines) that are typically found in LPAR image profile in Hardware Management Console.

A z/OS system running on zD&T uses devmap and overrides definitions in Input Output Definition (IODF) data sets used for IPL. In devmap, it’s essential to match the device numbers of DASD, consoles, non-SNA terminals for time sharing option (TSO) logons and Open System Adapter-Express with what is specified in the current IODF used by the z/OS system for IPL.

In the host z/OS system, relevant master console definitions in CONSOLxx in PARMLIB are:

CONSOLE DEVNUM(4100) 
NAME(L4100) UNIT(3270-X) AUTH(MASTER) 
PFKTAB(CPPSS) AREA(NONE) ROUTCODE(ALL)
DEL(R) SEG(19) CON(N) RNUM(19) RTME(1/4) MFORM(J,S,T)

The host z/OS system uses 3390 mod-9 DASD devices with device address ranging from C100 to C104, where C100 is the system resident volume (SYSRES) and C101 is the IODF volume.

In the host z/OS system, definitions in VTAMLST for non-SNA terminals for TSO logon are:

EXLOCAL  LBUILD                                                
EXL001   LOCAL TERM=3277,CUADDR=4101,FEATUR2=(EDATS,MODEL2),   
               USSTAB=USSN,DLOGMOD=DYNAMICB              

The host z/OS system uses OSA express in QDIO mode for TCPIP communication.

Corresponding TRLE definitions in VTAMLST are as follows:

TRL24P1 VBUILD TYPE=TRL 
MPC24P1 TRLE LNCTL=MPC, 
READ=2400, 
WRITE=2401, 
DATAPATH=(2402), 
PORTNAME=OSA24P1, 
PORTNUM=1, 
MPCLEVEL=QDIO 

The contents of LOADxx PARMLIB member in the host z/OS system are:

IODF     13 SYS1     ZOS      01                                     
INITSQA  0002M 0016M                                                 
IEASYM   (00,P0)                                                     
PARMLIB  SYS1.ZDT.PARMLIB                       
PARMLIB  SYS1.PARMLIB                           
PARMLIB  SYS1.IBM.PARMLIB                       
PARMLIB  USER.PARMLIB                           
SYSCAT   ZDTSS1113CICFCAT.ZDT.MCAT                    ICFCAT
SYSPARM  (P0,L)                                                      

To make the host z/OS system run on top of zD&T, no changes were made to CONSOLxx, LOADxx, non-SNA terminal definitions/TRLE definitions in VTAMLSTs or the IODF data set. We wanted to run zD&T under Linux User ID “ibmsys1.” Using this same User ID, we created devmap and defined the following for the host z/OS system to run under zD&T with three GB RAM and one CPU:

[system]
memory 3072m
processors 1
3270port 3270 # port number for non-SNA 3270 thru aws3274

[manager]
name aws3274 0001 # non-SNA terminals for console & TSO logon
device 4100 3279 3274 mstcon        	# master console
device 4101 3279 3274 tso 		# for TSO logon

[manager] # define network adapter (OSA) for communication with Linux#
name awsosa 0024 --path=A0 --pathtype=OSD --tunnel_intf=y # QDIO mode
device 2400 osa osa
device 2401 osa osa
device 2402 osa osa

[manager]
name awsckd 0002 # DASD definitions
device C100 3390 3390 /z/ibmsys1/z1090/disks/ZDTRS1
device C101 3390 3390 /z/ibmsys1/z1090/disks/ZDTSS1
device C102 3390 3390 /z/ibmsys1/z1090/disks/ZDTMS1
device C103 3390 3390 /z/ibmsys1/z1090/disks/ZDTOMV
device C104 3390 3390 /z/ibmsys1/z1090/disks/ZDTSMS

Mainframe OSA express console controller is typically used to get non-SNA terminals for consoles and TSO logon, whereas in zD&T, we can get non-SNA terminals with the help of the aws3274 device manager. In the above devmap definition, the port number in which the aws3274 manager should listen is mentioned in the [system] stanza by the “3270port statement,” which is 3270 (default).

Arunkumaar Ramachandran is a Senior IT Specialist at IBM India Software Labs. His areas of expertise include z/OS and z/VM. Arunkumaar can be reached at aruramac@in.ibm.com.



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