Teledyne LeCroy SAS Suite User Manual - Manual (Page 57)

SASSuite User Manual Version 6.25
LeCroy Corporation
47
Buffer Size The Buffer Size slide bar adjusts the recording buffer size
from 3.2 megabytes to 4096 MB. This option is used for
setting the maximum memory to be used for a 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 4096 MB of physical
memory in the Avalanche analyzer, there is additional information recorded with each
frame, such as timestamps and other system parameters, so the efficiency of the
recording is at least 60% (ratio of actual SAS or SATA traffic to physical memory).
Filtering and truncation will yield better efficiency. The actual 4096 MB of memory can
only be reached when symmetric data is recorded on all four ports.
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 or the Stop Recording button in the GUI is
pressed..