RDF System Management Manual

Auxiliary Audit Trails
HP NonStop RDF System Management Manual—524388-003
12-4
Takeover Ramifications
Takeover Ramifications
If an auxiliary extractor is running behind the master extractor when you issue a
TAKEOVER command, a transaction just committed on the primary system (and who’s
commit record was received by the master receiver) could be backed out on the
backup system.
This could happen under the following circumstances:
•
In addition to the MAT, you have configured RDF to protect one or more auxiliary
audit trails.
•
When the primary system fails, an auxiliary extractor is running behind the master
extractor. For example, the master receiver has received the commit record
associated with a particular transaction, but the auxiliary receiver is missing audit
data for that same transaction.
•
A committed transaction (whose commit record was received by the master
receiver just before the primary system failure) updated only a volume associated
with the MAT.
Usage of Master and Auxiliary Audit Trails
A master extractor must always be associated with the MAT even if no data volumes
are configured to the MAT. A master extractor is required because the MAT contains
audit records that preserve TMF control information required by RDF on the backup
system, and this control information is not stored in any auxiliary audit trail.
Using Expand Multi-CPU Paths
The use of Expand with ATM or Fast Ethernet provides considerable bandwidth, and it
is often sufficient to have a single Expand path driven out of a single processor.
If your RDF configuration is replicating auxiliary audit trails, however, the total amount
of audit data to be sent from the primary system to the backup system could be more
than a single Expand path can handle. If that is the case, you should use the Expand
multi-CPU path feature.
Expand multi-CPU paths enable you to spread the communications load over multiple
processors by connecting multiple Expand line-handler processes, each in a separate
processor, between two adjacent nodes. In an RDF environment, you would use this
feature to establish dedicated paths for the master extractor-receiver pair and multiple
auxiliary extractor-receiver pairs.
Suppose you will be configuring three extractor-receiver pairs: one for the MAT and
one each for auxiliary audit trails AUX01 and AUX02. Suppose further that both your
primary and backup systems have ten processors. For each Expand multi-CPU path,
you place the matching Expand line-handlers in the same processor on both systems.