when we un-monitor a server, (hoping for more licenses!!) the dpa_deadlock_capture is left, and deadlocks are not picked up in the system health xe.
I'm wondering if anyone has written a handy query to read the dpa_deadlock_capture, as it has a ring buffer target, and also - how do i get things to start going back to system health?
I can of course parse out the xml myself but i thought if someone else has already done it perhaps they could share.
sorry it took so long to reply - but, yes. Instances which are not being monitored have the trace, and the system_health trace is not capturing the deadlock graph - which means it is kind of a pain to get good deadlock information.
So when you put up this discussion I sent the questions and checked some with the DPA engineering team on this issue. The reply from them was "We are not touching the system_health session and I don't know about any behavior on SQL Server that should stop collecting the deadlocks when another session is created.
I verified and both the default system_health and dpa_deadlock_capture is collecting the deadlocks in ring buffer."
So if you are not seeing deadlock data on the default system_health trace it shouldn't be related to DPA. One issue might be what we internal call the Hydration problem.
4MB of BINARY data != 4MB of XML data => not all deadlocks appear in XML
Ring buffer works as FIFO (first in first out), so potentially, if ring_buffer will be full all the time, we will never have opportunity to see the first deadlocks (EES can collect also other events than deadlocks, and those events takes its place in ring buffer as well).
Default configuration depends on type of monitored SQL Server instance:
I don't know from what you list here if this is the case. You can always log a support case and we can investigate more.
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