Chapter 9. Initial performance considerations 221
9.2 Performance tests
We conducted a set of tests varying the number of managed servers and policy complexity,
while keeping the actual workload transaction rate (per server) relatively constant.
9.2.1 Environment
All supported platforms were chosen and configured as domain managers as illustrated in
Table . Domain manager server configuration
The number of managed servers was respectively: 63, 126, 252, 504. The same set of
measurements were conducted on all three different platforms.
Two different service policies were used during the measurements and they are summarized
in Table 9-1. All the service classes are defined with Response Time goals.
When we moved from the Simple to the Complex policy, we further filtered the workload to
utilize the additional transaction and service classes.
The number of rules (filters) or type of rule is essentially not a factor in domain manager
resource consumption because classification occurs on the “edge” managed server. We
utilized one filter per transaction class.
Table 9-1 Service policies summary
In order to simulate high numbers of real EWLM managed servers, we utilized an internal tool
for all of our tests. The tool essentially simulated the performance data being collected every
2 seconds on each of the individual managed servers. Hence the messages being sent from
the managed servers to the domain manager were real, though based on simulated input into
the individual managed servers. Special code was added to the EWLM managed servers,
allowing multiple managed servers to run on the same OS image. No part of the actual
domain manager processing was scaffolded or simulated.
Our model environment is an EWLM management domain with many OS instances (servers)
with each server being responsible for a single function (for example Web serving, application
serving, database) as illustrated in Figure 9-1.
Platform Processor
model
Processor speed Physical
memory
Network
adapter
Windows Server 2003
Enterprise Edition
x255 Xeon 4-way
@2GHz w/ht
3.8GB Gbit
AIX 5.2 ML03 (32bit) p630 7028-6C4 Power 64bit 1.4Ghz
4-way
7.0GB Gbit
i5/OS 4way of an i825
6way
4way of a 6way
rated at 6600 CPW
5.7GB Gbit
Policy Number
of service
classes
Number of
transaction
classes
Number of
process
classes
Number of
service
classes
utilized
Number of
transaction
classes
utilized
Number of
process
classes
utilized
Simple 5 20 1 5 20 1
Complex 20 80 1 20 80 1
222 IBM Enterprise Workload Manager
Figure 9-1 Application/server topology
A given server in the domain consisted of one application environment. Each server is
simulating roughly between 10 and 50 sub-transactions per second, which are spread across
these three application environment instances. We use here the term sub-transaction to
represent a piece (or hop) of a multi-tiered transaction. The actual transaction rate is not a
factor in the domain manager resource requirements. The number of unique combinations of
application environment instance—application environment—hop—transaction classes
having actual transaction counts (for example, completions) is a factor. To simplify, this could
be thought of as the number of different transaction classes that have qualified transaction
counts on a given server.
Table 9-2 shows some additional characteristics of the combined Policy/Application/Server
topologies utilized in our testing.
Table 9-2 Workload complexity
In other words, although the domain manager was monitoring five service classes and eighty
transaction classes in the total network for our simple policy definition, we assumed that an
individual managed server would only report on a single service class with three transaction
classes.
We are not recommending an installation try to predict all of these characteristics. This serves
to give a better appreciation for our topology characteristics and some of the additional
influencers of resource consumption. Generally, as these values increase, so does the
amount of data being transmitted to the domain manager and domain manager processing
and memory resources.
Policy Average number of
service classes
utilized per server
Average number of
transaction classes
utilized per server
Average number of servers a
given transaction class is
utilized on
Simple 1 3 1/7th of all managed servers
Complex 3 10 1/7th of all managed server
Apache1
Apache2
Apache3
Apache1
Apache2
Apache3
Apache1
Apache2
Apache3
Edge1Hop1
Edge2Hop1
Edge3Hop1
Apache1
Apache2
Apache3
Apache1
Apache2
Apache3
Apache1
Apache2
Apache3
AppServer1Hop2
AppServer2Hop2
AppServer3Hop2
Apache1
Apache2
Apache3
Apache1
Apache2
Apache3
Apache1
Apache2
Apache3
DBServer1Hop3
DBServer2Hop3
DBServer3Hop3
DM
1 Application environment per server
3 tier architecture - all trx are 3 hops
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