[Jakarta-jmeter Wiki] Update of "JMeterAndAmazon" by ob erman

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The "JMeterAndAmazon" page has been changed by oberman.
http://wiki.apache.org/jakarta-jmeter/JMeterAndAmazon

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New page:
=3D JMeter and Amazon =3D

=3D=3D Elastic Load Balancer (ELB) Issues =3D=3D

 * The ELB is a name, not IP, and suffers from DNS caching.  Make sure you =
use "-Dsun.net.inetaddr.ttl=3D0" when starting JMeter
 * For a given ELB IP, there seems to be a static mapping of client IP <-> =
backend instance.  This is a slightly complicated statement that assumes a =
some knowledge of how amazon in general, and ELBs in particular, work.  If =
it's still up, this page [[http://www.shlomoswidler.com/2009/07/elastic-in-=
elastic-load-balancing-elb.html]] has pretty much everything you need to kn=
ow.  But the basic idea is that the ELB is supposed to balance the inbound =
traffic to the currently known & healthy backend instances (e.g. the boxes =
you actually control).  At any given time, the ELB DNS name resolves to a p=
ool of ELB IP addresses (which grows or shrinks based on load).  The TTL on=
 an ELB name (which is owned & controlled by amazon, e.g. loadbalancer123.a=
mazon.com) is 60 seconds.  And again, in practice I've found the load balan=
cing to be per client/ELB IP, rather than per request.  =


 *Specifically, the behavior I've seen in JMeter is:
   *I start a test that generates a small amount of load forever
   *I check backend instances, and all load in on one box
   *On the JMeter box, I run "dig mydomain.com" and watch the TTL count dow=
n from 60 to 0
   *If the ELB IP changes, all load moves to a different backend instance (=
and if the ELB IP stays the same, it stays in the same place