PedalHarder
2 Iron

Re: Read Response time vs Read Miss response time.

SQL server is very bursty in nature, particularly with it's checkpoint writes (AKA lazy writes). You don't typically see them in Performance Manager data as the interval is too large. You may see the evidence in PM by looking at the FA queue stats. Check your FA queue stats and you will likely find excessive queuing which is causing your read times to elongate. You can confirm this on the host by running perfmon and looking and the read/write counters. Run it over a period of time at 1 second intervals and you will really get a good idea of the write bursts. I've seen 5000+ in one second.

The best way to avoid the impact of these writes is to assign more FA's to do the work. Make sure you have Powerpath to ensure the IO's are being distributed across the FA's.