RDF/IMP and IMPX System Management Manual (RDF 1.3+)

Lockstep Operation
Compaq NonStop™ RDF/IMP and IMPX System Management Manual—522204-001
14-4
The Lockstep Transaction
lockstep operation has completed and rely on RDF to ship the audit data to the
backup system as soon as possible.
LockStepNotDone (value is 31426)
The RDF gateway process cannot be started. This status has the same ramifications
as LockstepDisabled, and what your application does next is your decision.
The Lockstep Transaction
Remember, you must commit your business transaction before you call DoLockstep.
Thus, when the gateway process issues the lockstep transaction, all audit records
associated with your business transaction are guaranteed to be flushed in the audit trail
on the primary system before any lockstep audit is generated. Therefore, when the
lockstep audit is safely in the image trail on the backup system, you are also guaranteed
to have all audit information of your business transaction safely in the image trail as
well, because your business audit preceded the lockstep audit.
RDF Lockstep File
Each lockstep transaction involves a single update to a gateway-managed lockstep file.
This file is created by the lockstep gateway and it must only be updated by the gateway.
If you open the file and update data in it, you can potentially corrupt all future lockstep
operations.
When configuring the RDF configuration record, you must specify the name of the
volume on which you want the lockstep file to be located. This volume must be
configured to the Master Audit Trail (MAT), and either the entire volume or at least the
lockstep file must be protected by the RDF subsystem. You specify the volume by using
the following RDFCOM command:
SET RDF LOCKSTEPVOL volume
Where volume is a volume name and the volume is configured to the MAT.
Additionally you must ensure that you add an updater to protect either the volume or
the lockstep file.
The full file name is
volume.ZRDFLKSP.<control-subvol>. If you only need to
protect this file on this volume, then INCLUDE it when you configure the updater for
the volume.
The RDF lockstep protocol supports virtual disks, so you can store your database on
virtual disks managed by the Storage Management Facility (SMF). The RDF
LOCKSTEPVOL, however, must be a physical disk, and it must be configured to the
Master Audit Trail (MAT). Because the RDF lockstep file on the LOCKSTEPVOL is a
direct (physical, not logical) file, it can reside easily on a small portion of a physical disk
to store the file, and you can then subdivide the rest of the disk into virtual disks.