Teledyne LeCroy SAS Suite User Manual - Manual (Page 93)

SASSuite User Manual Version 6.25
LeCroy Corporation
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Conventional Single Buffer Recording
In a Conventional recording, the trace is recorded and stored in the analyzer buffer before
it is uploaded to the host PC. Recordings are thus limited in size to the maximum size of
the analyzer buffer. If you are planning to create a moderate-sized recording, this is a
good option to select. You set the buffer size and the trigger position, then begin the
recording. Once the recording is complete, the traffic is uploaded to the host PC.
If you are planning to create a large recording or are planning to let the analyzer run over
a several days, then select Spooled Recording. In a Spooled Recording, traffic is
uploaded periodically to the host PC--thus freeing analyzer buffer and allowing the
recording to continue.
Buffer Size - The Buffer Size slide bar adjusts the
recording buffer size from 1.6 megabytes to 2048 MB.
This option is used for setting the maximum memory to be
used for a Conventional recording.
The option mentioned above for truncating data payloads,
as well as filtering options which will be discussed later,
determine what information from the raw data stream is actually recorded into trace
memory. Also, although there are 2048 MB of physical memory in the SASTracer
analyzer, there is additional information recorded with each frame, such as timestamps
and other system parameters, so the efficiency of the recording ranges from about 37%
in the worst case to 75% in normal traffic and higher when packing is possible (ratio of
physical memory to actual SAS or SATA traffic).
Note: The Buffer Size slider bar is not linear and affords more granularity in the
smaller buffer sizes.
Trigger Position - The Trigger Position slider bar
allows the user to define the position of the trigger
within the recorded traffic. Essentially, this is
instructing the system when to stop recording. If the
trigger position is set to the end of the recording,
recording will stop immediately when the trigger
occurs. If the trigger is set to the start of the recording,
when the trigger occurs the system will continue to record until the buffer has filled again
and then stop (before the new data overwrites the trigger). Any intermediate setting
allows the user to see data both before and after the trigger occurred. You can adjust the
Triggering Position between 1 and 99% post-Trigger. Trigger Position is available only
when Manual Trigger or Event Trigger is selected as Recording type.
As an example, if the buffer size is set to 16MB, then for the following Trigger Position
settings, the amount of pre- and post-Trigger data is:
•
95% post-triggering: 0.8MB pre-trigger, 15.2MB post-trigger
•
75% post-triggering: 4MB pre-trigger, 12MB post-trigger
•
50% post-triggering: 8MB pre-trigger, 8MB post-trigger
•
25% post-triggering: 12MB pre-trigger, 4MB post-trigger
•
5% post-triggering: 15.2MB pre-trigger, 0.8MB post-trigger
Note: When a Trigger occurs, recording continues until the post-Trigger
amount of the buffer is filled.
Note: The buffer is limited to 1 GB when in trainer mode/configuration.