RDF System Management Manual

Preparing the RDF Environment
HP NonStop RDF System Management Manual—524388-003
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Data Communication (Expand) Resources
3. If all the TMF audit data is generated on volumes protected by RDF, subtract the
first EOF value from the second EOF value to obtain the number of bytes
generated during the 5-minute period. Then divide the number of bytes by 300
seconds to determine the amount of audit data generated in a second; for
example:
(11653120-11292672)/300 = 1202 bytes per second
The extractor does not necessarily transmit all audit records associated with a
particular transaction. For example, audit information associated with physical
operations is not transmitted. The reason for this is that the backup database is
maintained as a logically identical copy of the primary database, not as a physically
identical copy.
The data communications link should have at least two paths (multi-line Expand). Each
path should go through different communications carrier paths or switches, and each
should be able to transmit the peak data rate. See also Using Expand Multi-CPU Paths
in section 12.
It is almost impossible to calculate the RDF audit transmission rate from the TMF audit
generation rate alone.
HP has developed a sizing tool that can be used to predict accurately the Expand
bandwidth requirements between the primary and backup systems by simulating the
RDF extractor. That utility reads the TMF audit trails and generates detailed
information about TMF audit generation and RDF audit transmission activity. This
information is particularly useful when a single system supports multiple applications
and the database and RDF will only be configured to protect a subset of these
applications. This tool was designed and developed as part of the RDF Professional
Service.
Contact your service provider for further details.