In order to make sure you know what error code is returned from the controller at that point of time and eliminate any memory related problems, you could try performing the following steps:
1) Enable xml logging ----> dfm options set xmllogenabled=yes 2) Run a dfm host discover against the controller. 3) Check for the 'xml' trace.log for that controller, check for the 'perf-object-get-instances-iter-start' zapi and verify for the response from the controller.
You would need to run these steps when you hit the issue. So that you can correlate the logs with the timestamp the zapi was issued.
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