Recommendations For The Gen2 Capture Cards - Network Instruments GigaStor User Manual

After you have the RAM reserved for Observer, you must allocate it for the probe instances. Here are our basic
recommendations for allocating the memory. These are just recommendations and may be changed or modified
for your circumstances. If you are using a GigaStor, read this section, but also be sure to consider the information
in Recommendations for the Gen2 capture cards (page
How many probe instances will you have on this system? How are you using the probe instance(s)? Are you
using it to capture packets or to analyze statistics? After you know how you want to use the probe instance, you
can decide how to properly divide the memory amongst the probe instances, and further how you will allocate
the memory between the packet capture andstatistics queue buffers.
You want to create and use as few probe instances as absolutely necessary. Each probe instance you create
divides the memory pool into smaller chunks. The more probe instances you have, the more processing the
system must do.
For each probe instance determine:
If you want to mostly capture packets, then allocate 90% of the RAM to packet capture and 10% to the
statistics queue buffer. At a minimum, you should allocate 12 MB to collect statistics. If you are using
a GigaStor, you should allocate the vast majority of the RAM for the active probe instance to packet
capture.
If you want to collect statistics or trending data, or use analysis, then allocate 90% (or even 100%) of the
RAM to the statistics queue buffer.
If you want to do both, determine which you want to do more of and allocate the memory accordingly.

Recommendations for the Gen2 capture cards

Unless specifically stated, all information in this section applies to both the 1 Gb Gen2 card, 10 Gb Gen2 card,
and 40 Gb Gen2 card. The Gen2 card is only available in hardware products from Network Instruments.
There are additional requirements and considerations if you are using a GigaStor. A GigaStor may have one of
several different capture cards installed. Here are some special configuration issues to consider when dealing
with a Gen2 capture card:
For a 1 Gb Gen2 card, you need a minimum of 100 MB for the probe instance that monitors any Gen2
card. Allocating less than 100 MB for a probe instance monitoring a Gen2 card may cause instability.
If you are using a 10 Gb hardware accelerated probe instance, you must have at least 80 MB for both
packet capture and the statistics queue buffer. No packets are captured if either or both are below 80
MB. The 10 Gb hardware accelerated probe may only have one probe instance associated with it. 80 MB
is the minimum, but with network traffic speeds of 10 Gb, 80 MB will not be able to buffer much traffic.
Consider substantially raising this amount. The more RAM that you can allocate to packet capture and
statistics, the better your GigaStor probe will perform.
When using multiple probe instances on a GigaStor, ensure that only one probe instance is associated
with the Gen2 card. (If you are using virtual adapters to monitor disparate networks, then you may
have more than one active instance bound to the Gen2 card.) For performance reasons, all other probe
instances should be associated with a different network card.
If you feel a Gen2 card is not performing as expected, ensure that there is only one probe instance bound to it.
If there is more than one, verify that the other probe instances are not collecting any statistics. It is possible that
the probe instance you are looking at is not collecting any statistics, but one of the other probe instances may
be. (This is only an issue if there are multiple probe instances connected to the Gen2 card. This does not apply if
the other probe instances are connected to a regular network card.)
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