perfSONAR User Q&A and Other Discussion

[Andrew Lake <>]

All,

As some of you may have noticed on our mailing list, a few users have observed a bug in the 3.2.1 version of the toolkit where their OWAMP tests are not listed when clicking "One-way Latency" under "Service Graphs". We have uploaded a fix for this bug to the yum repository, so all NetInstall users may apply the fix by running 'yum update'. For LiveCD users, we will have a new ISO available in a few days that you can download.  A more detailed description of the bug is below:

How do I know if I have encountered he bug?

First and foremost, this only applies to hosts running one-way latency tests, so having a host with one-way latency tests is a requirement for encountering this bug. Assuming you are looking at a host with one-way latency tests configured, you can tell you've encountered this bug a few ways: 

1. If you load the "One-way Latency" page under "Service Graphs" and no tests are displayed under "Active" or "Inactive" tests. 

    * If you have test under "Inactive" but nothing under "Active" this is NOT a result of this bug. We recommend you check your configuration and email the list if you need help solving such a problem.

2. If you want to dig a little deeper, you can also tell that the bug has been encountered if running following command on your toolkit host returns "Illegal division by zero":

$ perl /opt/perfsonar_ps/serviceTest/cgi-bin/getData.cgi ma_url=http://localhost:8085/perfSONAR_PS/services/pSB eventType=http://ggf.org/ns/nmwg/characteristic/delay/summary/20070921

What causes the bug?

If an owamp test fails it may lead to a value being stored in the database that causes a divide by 0 error for the owamp graphing interface. 

Is any of my data lost due to this bug?

No, the bug itself is a display issue and will NOT cause data loss. If you encounter the bug though, it is due to a failed test so you may have deeper network or configuration issues that need investigation.

How do I fix it:

Current NetInstall users may run 'yum update'.

All new Netinstall users will automatically download this fix during the regular install process.  

LiveCD users will need to wait a few days until a new LiveCD is available.

Please let us know if you have any questions.

Thank you,

Andy Lake