Looking at Netapp’s sysstat -x 1 (or u if your screen isn’t wide enough) output live during an issue can be invaluable troubleshooting information, particularly the CP, or consistency point, types.
The one you don’t want to ever see are back to back types, b. This means the system can’t cope with the amount of data it needs to write; it’s trying to flush one half of the NVRAM to disk before the other half has finished. This increases latency which is the key metric in the ‘feel’ of how responsive a storage system is.
When a storage system’s latency is high then everything else pretty much suffers.
So if you’re told about an issue after the fact you generally can’t out of the box get historical info on these counters for a post mortem. Thankfully you can configure NetApp’s now free monitoring system DFM/OnCommand with Performance Advisor to log these counters.
Log into your DFM/OnCommand server, ours runs on Linux but the same commands are run from a Windows command prompt
[root@netapp ~]# dfm option set perfAdvisorShowDiagCounters=Enabled
Changed performance advisor show diag counters to Enabled. Warning: You are enabling diagnostics counters; these counters are meant for use by NetApp technical support only.
You must now restart the server service:
dfm service stop server[root@netapp ~]#
dfm service start server
Restart the DFM
[root@netapp ~]# dfm service stop server
Service: server stopped.
[root@netapp ~]# dfm service start server
Service: server started.
In Performance Advisor, go to Setup > Hosts. Select the host you want to view CP data for and edit its data collection.
Under enabled counters go to wafl where you will see the cp_count. This is counter we are interested in. You can modify the sample rate and retention period if needed. (I seem to have added this part already)
In order to view the collected data you have to create a custom view. Go to Setup > Custom Views > Add
Set the view name to be something like <filer name> wafl CP and choose Particular Objects
Click on Add Chart
Name the Chart the same as the view
Choose the line graph type
Select Catagory wafl and the required storage system
Expand storage system and scroll down to the cp_count section
Add all the entries in that section
Add the chart with the wafl:cp_count counters.