<story><title>Has Amazon EC2 become over subscribed? (2010)</title><url>http://alan.blog-city.com/has_amazon_ec2_become_over_subscribed.htm</url><text></text></story><parent_chain></parent_chain><comment><author>dotBen</author><text>&lt;i&gt;I&apos;m loathed to perpetuate a 3 year old article, but...&lt;/i&gt;&lt;p&gt;One of the key contributing factors to this kind of network degradation of AWS (/or other cloud vendor) is the abundance of the &quot;bad neighbor test&quot; - where a client performs tests to see if they can achieve a &lt;i&gt;&apos;preferred&apos;&lt;/i&gt; amount of CPU/IO on the host of their new instance.&lt;p&gt;Resource sharing rules at the host level actually means that if everyone is trying to max out their instance, you would still get the equal share you are entitled to and guaranteed with your instance, so what the bad neighbor test really means is whether you can actually go into your neighbor&apos;s CPU allocation due to their under-use.&lt;p&gt;Well, if &lt;i&gt;everyone&lt;/i&gt; does that then the system degrades as &lt;i&gt;someone&lt;/i&gt; has to a party using less than their allocation and the amount of instance spots that don&apos;t fail the &apos;bad neighbor test&apos; become non existant.&lt;p&gt;The overall health of the entire network would actually be better if folks didn&apos;t do this practice and instead everyone simply evened out their use across their instances that enjoy additional resources and stuck it out with the %age of their instances that only achieved their guaranteed minimum resource use and no more.&lt;p&gt;My company uses another &quot;cloud-like&quot; vendor and although we don&apos;t perform &apos;bad neighbor&apos; tests upon new instances, it is fair to say our application benefits from the fact that the majority of the instances on their network are under-utilized and we can push into the max CPU of the host beyond the limits we pay for.  Where instances do share &apos;bad neighbors&apos; (ie we can only get what we paid for and no more - boo hoo, etc) we still keep the instance but simply route around that and distribute less load than on other nodes in our network.&lt;p&gt;That doesn&apos;t become the most cost effective mechanism, but the &quot;savings&quot; of the &lt;i&gt;&apos;bad neighbor test&apos;&lt;/i&gt; are probably negligible and ironically by not doing this we become the &quot;good neighbors&quot;.</text></comment>
<story><title>Has Amazon EC2 become over subscribed? (2010)</title><url>http://alan.blog-city.com/has_amazon_ec2_become_over_subscribed.htm</url><text></text></story><parent_chain></parent_chain><comment><author>trotsky</author><text>I was trying to figure out how this guy could be so behind the times - just discovered internal network latency at AWS?&lt;p&gt;Then I saw:&lt;p&gt;Published: 
9:01 AM GMT, Tuesday, 12 January 2010</text></comment>