The Two I/O Fallacies
The IOPS Fallacy
I have more than enough IOPS to handle the workload.
Workloads are processing 30-40% slower than they need to be due to Split, Small, Random I/O patterns generated by the Windows O/S.
Sequential I/O ALWAYS outperforms Random I/O.
Only a small percentage of total I/O capacity is used at any one time.
We get a false sense of performance due to high IOPS and I/O Response time ratings.
V-locity optimizes the work being done, not the spare capacity that isn’t being used.
I/O Response time can be misleading
Faster I/O response time is better.
One individual smaller I/O transfers faster than one individual larger I/O.
This also doesn’t take into account:
Split vs. Contiguous I/O
Random vs. Sequential I/O
The individual response time of each I/O has been overprioritized in the performance analysis equation.
Overall throughput is always slower when data is transferred with Split, Small, Random I/O.
Overall throughput is always faster when data is transferred with Contiguous, Larger, Sequential I/O.