HP NonStop SSL Reference Manual page 83

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CPU consumption
Since Multi-CPU paths have a separate LH process for each line, the HP NonStop SSL processes can be
configured to use the same CPU, reducing message-system hops between CPUs for the Loopback
communication, resulting in a lower CPU consumption.
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Load-balancing
A Multi-CPU path will assign a particular line to any pair of communicating processes. Hence, if a single pair
of communicating process is generating a high traffic load, such as a FUP DUP or an RDF Extractor/Replicator,
this traffic will burden a single CPU.
Multi-Line paths will distribute traffic evenly across all available lines, independently of the number and CPUs
of the processes communicating over EXPAND. Load will also be re-distributed dynamically and transparently,
if a CPU of a HP NonStop SSL EXPANDS process is heavily loaded by processes with a higher priority.
Hence, bandwidth can be preserved, even if the HP NonStop SSL processes run at a low priority to avoid
impact on critical application processes.
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Fault-Tolerance
With Multi-CPU paths, a single line is assigned to a communication link between a requestor and a server. If
this line goes down, a communication error will be reported to the requestor, and the communication link will
have to be re-established.
A failure of a single line with a Multi-line path will be completely transparent to the application and the traffic
will be re-routed automatically.
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Throughput
The highest maximum throughput can be achieved with Multi-CPU paths. Measurements showed a throughput
of up to 1,5 MB/s per CPU for FESA/100Mbit connected systems, with a linear scalability for multiple
requestor/server pairs running in different CPUs (e.g. 6MB/s 1with 4 pairs).
Multi-line paths have a lesser maximum throughput, as all traffic is handled by a single LH process.
Measurements have shown a throughput of 1,4 MB/s for FESA/100Mbit connected systems with a single
requestor server pair and a total maximum throughput of about 3 MB/s with multiple pairs.
Optimizing Throughput
The following configuration properties & setup can impact the overall throughput over an EXPAND over SSL path:
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LIF DataForwardCount (DFC) and DataForwardTime (DFT)
Reducing the values DFC and DFT can increase the throughput for an EXPAND over SSL line. Setting DFT
and DFC to the smallest possible values will minimize response time.
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CPU selection of HP NonStop SSL EXPANDS processes with multi-line paths
Starting a HP NonStop SSL EXPANDS line process in primary CPU of a EXPAND line handler process
handling multi-line path can severely decrease the overall throughput. For an optimal performance even in case
of a takeover of the line handler backup, it is recommended to run the HP NonStop SSL EXPANDS processes
in CPUs not used by the LH process.
Multi-Line Path Installation Sample
The following sample configuration illustrates how to optimize throughput, distribute CPU load and achieve fault-
tolerance.
Assumptions:
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\SYSA and \SYSB to be connected over EXPAND SSL
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Systems have 8 CPUs each
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TCPIPv6
Configuration:
The following figure shows a complete setup:
HP NonStop SSL Reference Manual
Configuration • 83