Chapter 1. IBM Enterprise Workload Manager overview 17
In other words, in an EWLM environment, a DB2 transaction no longer has the same meaning
as one enclave transaction, or a unit-of-work between two DB2 commits. In our case, a
transaction becomes an ARM work request, and its elapse time is simply the duration of
receiving and processing a database request message to DB2 from the DRDA requestor.
Figure 1-10 illustrates where in monitor reports you can find the number of ARM and enclave
transactions.
Figure 1-10 ARM and enclave transaction relationships
The EWLM Control Center reports the number of transactions (ARM work requests). For
DB2, this number of ARM transactions (ARM work requests) is reported as messages in the
Distributed Activity and DRDA REMOTE LOCSDB2 sections of the Performance Expert
accounting and statistics reports.
An enclave transaction corresponds to an SRM transaction and its number is reported as
occurrences, DBATS, and commits by DB2 Performance Expert, and Transaction Ended by
RMF™ in the Workload Activity report in the Service class and Report class.
So, as far as the relationship between EWLM and z/OS WLM goes, at this time they are
driven by different service policies, operate independently, and have different scopes. EWLM
manages multi-tiered application environments that may run on different hardware platforms
and operating systems including z/OS and has an end-to-end scope of control. The z/OS
WLM scope is limited to z/OS platforms. The future might see functionality that converges
these policies.
1.3.2 Workload management on pSeries
For pSeries installations there are several platform-specific workload management tools
available. This includes, for example, AIX Workload Manager (WLM) and Partition Load
Manager (PLM). The question is how does the Enterprise Workload Manager (EWLM) fit into
this picture? Are these workload management tools competitive products or are they
complementary to each other? Can they coexist or do customers need to make a decision
Enclave
create
(IWMECREA)
Enclave
delete
(IWMEDELE)
SRM transaction
arm tranarm tran
Application & Server Topology Tableview (EWLM)
Distributed Activity Messages (DB2 PE)
DRDA Messages (DB2 PE)
Reported as
Reported as
Occurrences (DB2 PE)
DBATs (DB2 PE)
Commits (DB2 PE)
Transaction Ended (RMF)
arm tran
arm tran
arm work
request
(arm tran)
Legenda:
arm_start_transaction
arm_stop_transaction
18 IBM Enterprise Workload Manager V2.1
about which of them to use in their environment? We discuss and clarify these issues in the
following paragraphs.
AIX Workload Manager is a free-of-charge feature of the AIX operating system and works
within one AIX image. It can manage CPU and memory resources as well as I/O bandwidth
for an individual server or a partition. The aim is to prioritize specific applications or processes
within a single operating system instance. If you have three competing applications running
on one server, for example, AIX WLM can make a prioritization according to customer needs
and give different a CPU time for each application, leading to different performances for the
competing applications. This is shown in Figure 1-11.
Figure 1-11 AIX Workload Manager (WLM)
AIX Workload Manager is a resource-based workload management tool. This means the
customer defines the amount of resources that each application should get relative to other
applications in case of resource contention. The actual performance goal is unknown to WLM
— it only knows the relative share of resources between applications. Terms like
transactions
and
response times are unknown and irrelevant to WLM and can therefore not be managed or
monitored.
Partition Load Manager (PLM) is a cross-partition workload management tool within a
partitionable pSeries server. Instead of having competing applications within one AIX image
as with WLM, PLM deals with competing partitions within a p5 server. PLM has no knowledge
about the applications running on each partition. It only compares the CPU and memory
utilization of the partitions and allocates free resources or shifts resources between partitions
according to the configuration, as shown in Figure 1-12. The main advantage is that in case of
changing workloads in the partitions, PLM automatically reconfigures resources according to
the policy.
AIX Workload Manager (WLM)
AIX Workload Manager (WLM)
Resource-based workload management within one AIX image
0
20
40
60
80
100
CPU time in %
Test1 Test2 Test3 Test4 Test5
Class 1
Class 2
Class 3
Tiers 1 1 1 1 1 2 1 1 2 2 2 1 1 1 1
Shares --- --- 80 40 - --- ---
Limits --- --- --- --- 10 - -
0
20
40
60
80
100
CPU time in %
Test1 Test2 Test3 Test4 Test5
Class 1
Class 2
Class 3
Tiers 1 1 1 1 1 2 1 1 2 2 2 1 1 1 1
Shares --- --- 80 40 - --- ---
Limits --- --- --- --- 10 - -

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