Systems & Software Talk 

"Other or Supplier" Bottleneck

Recently I ran a performance test that left a few of we the test watchers/analyzers scratching our heads. I scratched a few more hairs off my own and revealed even more bare skin. This test was executed across a full DS3 hose - 45 Mbps.

The results, specifically the bandwidth/throughput chart - showed a flattline at 27Mbps, despite increasing simulated user load that graphically stairstepped through and above that line. Investigation showed we had full DS3 locally. So, we called our internet provider and asked if they had any issues during the time frame of the test. They replied, "None!" Twenty four hours later, we ran the same test. We went above and beyond the previous night's 27Mbps "limit" on the hose to the true demand of the test at about 38Mbps.

Mysterious? Yah, you betchah!  Did our provider think we would never know we were getting less than what we were paying for? Probably!

Learnings:

1. Bottlenecks can be supplied by service suppliers.
2. When looking over results, scrutinize throughput if pushing high volumes relative to the hose. Scrutinize it for other reasons as well. Make sure you aren't getting hosed, or in this case - you are getting properly hosed. 
3. If one is balding, find another way to exhibit puzzlement rather than scratch the head. Bite one's finger nails perhaps?