RDF System Management Manual

Process-Lockstep Operation
HP NonStop RDF System Management Manual—524388-003
14-5
Multiple Concurrent Lockstep Operations
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.
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.