[Halld-online] [New Logentry] Follow-up Re: DAQ holds 150nA on the diamond

[davidl at jlab.org]

Logentry Text:
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The screencaps below were taken of both iotop and iftop during times of "good" livetime and "bad" livetime. The first image is of the disk performance when the livetime is bad and the second when it is good. It shows that the SEB (Single Event Builder) component is writing at 207 MB/s at the same time the ER (Event Recorder) is writing at 595 MB/s. In the second image the SEB does not appear. (The other process with "JMirror" are copying to tape and are reading from a different partition.) This looks as though the SEB is trying to use the disk for something at that is interfering with the ER's ability to utilize the full bandwidth.

The 3rd and 4th images show the network rate for the infiniband connection. The total values for the TX and RX rates (bottom right corner) show data is coming in and leaving at about the same rate. The transfer out is to the monitoring system currently hosted on gluon48. What these indicate is that there is no other source of competition for the bandwidth of data being transferred in through the IB interface. As a reminder, the IB interface is rated at least to 40GB/s. In practice we know it can handle at least 1GB/s input and 1GB/s output simultaneously. The conclusion is that the network is likely not the source of the drop in livetime.


[figure:1]

[figure:2]

[figure:3]

[figure:4]


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This is a plain text email for clients that cannot display HTML.  The full logentry can be found online at https://logbooks.jlab.org/entry/3462731
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