I got into a discussion in the Performance Testing group on LinkedIn which raised a question that we had answered internally, but had neglected to share with our customers – how much bandwidth do our cloud engines have available?
Before I proceed, I must make this disclaimer: our cloud engines run on Amazon’s EC2 infrastructure, so the rules that apply there also apply to our cloud engines. Amazon does not make any guarantees for bandwidth, so anytime your test results look suspicious, we … Continue reading »
When diagnosing performance problems with our clients websites, it is not uncommon for the bandwidth to come into question. Very often, the bandwidth chart will show a distinct plateau and it can be difficult to determine if this is cause or effect. This example shows outgoing server bandwidth (green) as the users (blue) ramp up. It could be interpreted as a bandwidth limitation around 8Mbps. In this case it is not – the limitation is elsewhere in the system.
It can be challenging to prove that bandwidth … Continue reading »
Is your load balanced website using more bandwidth under load than a single server would? In a previous article (“Status code 200 didn’t match expected: 304”), we discussed how a website may return full data content back to a client, even when the browser had the resource cached. If you believed that adding an extra server and a load balancer will increase your performance, this can be an unsettling surprise. The problem arises when two web servers are delivering different Entity Tags for the same static resource:
In … Continue reading »





