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Latency metrics

Question asked by Andrew Rolt on Feb 11, 2016
Latest reply on Apr 22, 2016 by Tien Lee

In the Nimble GUI and also Infosight, do the average read/write latency numbers include performance data from all volumes, including Non-Cached?  I'm seeing some very high average read times (ie: 30+ ms) and I'm finding it more work to track down where the high latency is coming from.  I'm assuming that it is looking at the whole array, which means its averages don't really mean much when troubleshooting high latency like that? I know that my cache is also a bit under-provisioned, so I'm looking at upgrading that.

Overall, my IOPs, Throughput, and CPU are very low (CS210), but I have higher average latency overall than I think I should be achieving.

 

ie: I have an Exchange 2007 VM that has 3 volumes/datastores attached - os, db and logs.  Logs is uncached using the "exchange log" policy.  Infosight tells me that the average latency on this VM is 9ms.  But, is that solely because of the uncached logs volume? I have to drill down into each volume to determine that.

 

I'm not sure why I'm writing this post. Perhaps to ask if it's possible to only see cached volume latency performance? We all know that uncached volumes are going to have high latency.  Those volumes are throwing off the performance data that we call care about and making the overviews and averages much less useful.

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