HP Archive Backup System for OpenVMS Guide to Operations
HP Archive Backup System for OpenVMS Guide to Operations
HP Archive Backup System for OpenVMS Guide to Operations
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Remote Devices<br />
8.4 Moni<strong>to</strong>ring and Tuning Network Per<strong>for</strong>mance<br />
Recommendation:<br />
Line receive buffers<br />
The PIPELINE QUOTA can be increased <strong>to</strong> 45,000 allowing 30 packets <strong>to</strong> be sent be<strong>for</strong>e a<br />
packet is acknowledged (in an Ethernet network). However, per<strong>for</strong>mance improvements have<br />
not been verified <strong>for</strong> values higher than 23,000. It is important <strong>to</strong> know that increasing the value<br />
of PIPELINE QUOTA improves the per<strong>for</strong>mance of RDF, but may negatively impact per<strong>for</strong>mance<br />
of other applications running concurrently with RDF.<br />
Similar <strong>to</strong> the pipeline quota, line receive buffers are used <strong>to</strong> receive data at a constant rate.<br />
Default:<br />
The default setting <strong>for</strong> the number of line receive buffers is 6.<br />
Recommendation:<br />
The number of line receive buffers can be increased <strong>to</strong> 30 allowing 30 packets <strong>to</strong> be received at a<br />
time. However, per<strong>for</strong>mance improvements have not been verified <strong>for</strong> values greater than 15 and<br />
as stated above, tuning changes may improve RDF per<strong>for</strong>mance while negatively impacting<br />
other applications running on the system.<br />
8.4.2 DECnet-Plus (Phase V)<br />
As stated in DECnet-Plus(Phase V), (DECnet/OSI V6.1) Release Notes, a pipeline quota is not<br />
used directly. Users may influence packet transmission rates by adjusting the values <strong>for</strong> the<br />
transport’s characteristics MAXIMUM TRANSPORT CONNECTIONS, MAXIMUM<br />
RECEIVE BUFFERS, and MAXIMUM WINDOW. The value <strong>for</strong> the transmit quota is determined<br />
by MAXIMUM RECEIVE BUFFERS divided by Actual TRANSPORT CONNEC-<br />
TIONS.<br />
This will be used <strong>for</strong> the transmit window, unless MAXIMUM WINDOW is less than this quota.<br />
In that case, MAXIMUM WINDOW will be used <strong>for</strong> the transmitter window.<br />
The DECnet-Plus defaults (MAXIMUM TRANSPORT CONNECTIONS = 200 and MAXI-<br />
MUM RECEIVE BUFFERS = 4000) produce a MAXIMUM WINDOW of 20. Decreasing<br />
MAXIMUM TRANSPORT CONNECTIONS with a corresponding increase of MAXIMUM<br />
WINDO may improve RDF per<strong>for</strong>mance, but also may negatively impact other applications running<br />
on the system.<br />
8.4.3 Changing Network Parameters<br />
This section describes how <strong>to</strong> change the network parameters <strong>for</strong> DECnet Phase IV and DECnet-<br />
PLUS.<br />
8-4 Remote Devices
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