Below are answers to questions asked during the webinar. If you have additional questions, please contact Craig Shallahamer (Craig.Shallahamer@me.com) or Janis Griffin (Janis.Griffin@solarwinds.com).
Q: What is the average IO response time?
A: Once the response time for an IO calls exceeds to 10ms, experience has taught me there is a good chance users are not pleased with performance. Also, I have yet to encounter a vendor who says, "Buy my IO subsystem because it can return an IO in 10ms!"
Q: Will the Solarwinds product read the statspack information?
A: SolarWinds DPA reads from the virtual or fixed tables. For example, x$ksuse and x$ksusecst. It does not look at the AWR or proprietary tables of Oracle. If you have Oracle SE, DPA can really help you identify your bottlenecks and point you in the right direction in fixing them.Will the Solarwinds product read the statspack information?
Q: How do you deal with queries that run fine only after stats are updated against the objects?
A: If you have data that is rapidly changing so that statistics are out of date, you may want to look at dynamically sampling the statistics. The OPTIMIZER_DYNAMIC_SAMPLING parameter can be set at the system or session level. You can also use a DYNAMIC_SAMPLING query hint for specific queries - however, you may want to create a baseline for this instead of putting hints in the query itself.
Q: DPA doesn't rely on AWR to get it's information. It uses the virtural or fixed tables.
A: Correct, if you have Standard Edition, you won't have AWR so you DPA can be an alternate solution.
Q: What about tuning with statspack? Not AWR.
A: Statspack and AWR all reference the virtual or fixed tables to get their respective information.
Q: Support other products like MaxDB or SAPDB ?
A: No planned support for SAP MaxDB. We monitor SAP ASE and we are currently reviewing adding MySQL to the mix.
Q: Suppose there is only one database running on a server. Can you relate OS CPU utilization to database CPU time?
A: There are 2 metrics in DPA that you can reference that shows OS CPU Utilization and DB CPU Utilization. DB CPU contributes to OS CPU utilization as will other instances or non-Oracle production CPU consumption. Knowing both the OS CPU utilization and DB CPU helps you better understand the sitaution.
Q: For 'general' performance issues, what would be the AWR snapshot window (end - start) that you would use?
A: Start with a one hour snapshot. Rarely will the snapshot be larger becasue performance related peaks and valleys will be smoothed so much, it is easy to missunderstand the performance sitaution. If the more intence and spike-like your application activity, the shorter your shanpshot will be. Remember, the goal is to capture data that will highlight and expose problems. Too big a snapshot will smooth out the spikes and too short a snapshot captures more data than you need plus the capture process could burden your production system.
Q: How will licensing change with multitenants ?
A: We currently only support single tenant databases.
