RDF System Management Manual for J-series and H-series RVUs (RDF 1.10)

Multiple Concurrent Lockstep Operations
Because DoLockstep suspends the calling application until the associated lockstep transaction
commits on the backup system, a single application process cannot have more than one lockstep
operation in progress at any one time.
Multiple application processes, however, can invoke DoLockstep concurrently.
If called while idle, the RDF gateway immediately initiates a lockstep transaction to perform the
requested lockstep operation (one calling process, one lockstep transaction).
If called while it has a lockstep transaction active, the RDF gateway merely queues the request.
When the current lockstep transaction commits, the gateway initiates a new one that performs the
lockstep operation collectively for all of the queued requests (multiple calling processes, one lockstep
transaction).
Because the business transactions of each application process must have committed on the primary
system before the process called DoLockstep, the audit data for those is guaranteed to be in the
Master Audit Trail (MAT) when the lockstep transaction begins. Thus, when the lockstep audit data
is committed on the backup system, all audit data generated in the MAT prior to that data is also
guaranteed to be committed on the backup system.
Lockstep and Auxiliary Audit Trails
You can use the lockstep protocol for business transactions involving files or tables on volumes that
are configured to auxiliary audit trails. In such a case, the lockstep protocol behaves exactly as it
would if all volumes were configured to the MAT. Remember, however, that you must still configure
an RDF lockstep volume for the lockstep file, and this volume must be configured to the MAT.
The Lockstep Gateway Process
The RDF lockstep gateway process is managed by the Subsystem Control Facility (SCF). To start a
lockstep gateway process, you must create and execute an SCF script file. The recommended script
settings are:
ASSUME PROCESS $ZZKRN
ADD #LSGO, &
NAME $ZLSGW, &
CPU FIRSTOF (1,2,3), &
PROGRAM volume.subvolume.LSGO, &
STARTMODE APPLICATION, &
STARTUPMSG "ENABLE <extractor-process-name>", &
AUTORESTART 10
START #LSGO
For detailed information about these attributes, see the information about configuring and managing
generic processes in the SCF Reference Manual for H-Series RVUs. For some attributes, however,
restrictions apply when the attributes are used with a lockstep gateway process.
NAME
This attribute must be $ZLSGW. If you specify anything else, the lockstep gateway stops and you
cannot perform lockstep operations. This means you can only have a single lockstep gateway
process running on your primary system.
PROGRAM
This attribute specifies where the RDF gateway object code resides. Typically, that location is the
same volume and subvolume where all of the other RDF software resides. The object name is LSGO,
and that you must fully qualify the name. For example, you might specify the PROGRAM attribute
as $SYSTEM.RDF.LSGO.
Multiple Concurrent Lockstep Operations 295