Sdr updater processes, Normal vs. takeover operations, Ems messages – HP Integrity NonStop H-Series User Manual
Page 48: Replication operations, Sdr updater processes 4-8, Normal vs. takeover operations 4-8, Ems messages 4-8, Replication operations 4-8
SDR Operations
HP NonStop SQL DDL Replicator User’s Guide —545799-006
4-8
SDR Updater Processes
SDR Updater Processes
The SDR monitor is responsible for monitoring all RDF activity. It does so by
monitoring RDF events sent to collector $0. The SDR monitor also makes a periodic
check of RDF and eventually makes the proper adjustments, even if the RDF events
are not available. When the SDR monitor detects an active RDF subsystem, it starts an
SDR updater process on the RDF backup system.
The SDR updater monitors events sent to the EMS collector that is configured as the
RDF LOGFILE. Although RDF always sends events to both $0 and any configured
LOGFILE, some installations might have a filter to eliminate RDF events. The SDR
updater depends on analyzing RDF events for proper operation.
Although the SDR updater is started and managed from the primary RDF system, the
SDR monitor must also be executing on the backup system.
Each SDR updater manages a specific RDF configuration. By RDF configuration, we
refer to the configuration identified by an RDF control subvolume of format node[suffix-
character]. If there are multiple active RDF control subvolumes, the SDR monitor will
start multiple SDR updater processes, one for each control subvolume. For example, if
on system \PRIM there are RDF control subvolumes PRIMA and PRIMB, there will be
two SDR updaters on the backup system, one for PRIMA and one for PRIMB.
Normal vs. Takeover Operations
When RDF is operating in normal mode, the SDR monitor on the primary RDF system
manages the SDR updater on the backup system. When RDF is operating in takeover
mode, it is assumed that the primary system is unavailable; the SDR monitor on the
backup system manages the SDR updater.
EMS Messages
In contrast to RDF, each SDR component, including the SDR updater, logs all EMS
events to the system that it was started from. When RDF is in normal mode, all SDR
EMS events are sent to the primary system EMS collector. When RDF is in takeover
mode, all SDR events are sent to the backup system EMS collector. This maintains a
better time line of all SDR events and avoids problems comparing primary and backup
EMS logs.
Replication Operations
Replicating and executing DDL statements entails the following operations:
Creating the SDR Depot Files on the Backup