Active Memory Expansion

Active Memory Expansion

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Description: Topics discussed include Expand memory beyond physical limits, More effective server consolidation, Run more application workload / users per partition, Run more partitions and more workload per server, Sample SAP ERP Workload, Active Memory Expansion -CPU & Performance, Active Memory Expansion Product Structure, Active Memory Expansion Decision Making, and more.

 
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Contents:
Mark Olson olsonm@us.ibm.com February 2009

Active Memory Expansion

� 2010IBM Corporation

IBM Power Systems

Active Memory Expansion
Effectively up to 100% more memory

True memory

True memory

True memory

Expand memory

Expand memory

Expand memory

True memory

True memory

True memory

Expand memory

Expand memory

Expand memory

POWER7 advantage for AIX 6.1 Expand memory beyond physical limits More effective server consolidation
Run more application workload / users per partition Run more partitions and more workload per server

� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion � Basic Concept
120 GB LPAR1

96 GB LPAR1

MM MM MM MM MM MM MM MM MM MM MM MM

ory mem and : exp ion o1 enari ed partit Sc rain const 20 GB 1 96

in

MM MM G MM MM G MM MM G MM MM G MM MM G MM MM G

Assumes 25% expansion

M G

Physical/true memory Gained memory capacity
� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion � Basic Concept
120 GB LPAR1

96 GB LPAR1

MM MM MM MM MM MM MM MM MM MM MM MM

ory mem and : exp ion o1 enari ed partit Sc rain const 20 GB 1 96
Scen a capa rio 2 � H c o capa ity, use a ld LPAR1 d city fo r LPA ditional 96 R 96+4 8=1 2 44 G B

in

MM MM G MM MM G MM MM G MM MM G MM MM G MM MM G
96 GB LPAR1

Assumes 25% expansion

48 GB LPAR2

M G

Physical/true memory Gained memory capacity

MM G G MM G G MM M G MM M G MM M G MM M G

MM MM MG MG MG MG

Assumes 50% expansion

� 2010 IBM Corporation

IBM Power Systems

Sample SAP ERP Workload, Single Partition (DataBase + AppServer)
Without Active Memory Expansion
Partition utilization
Memory: 100% (18 GB) CPU: 46% (12 cores in LPAR)

With Active Memory Expansion
Partition utilization
Note: Most of the CPU increase is due to additional work done on server

Memory: 100% (18 GB true) CPU: 88% (12 cores in LPAR)

Memory capacity is the bottle-neck
CPU is under-utilized Handles 1000 simulated users

Higher throughput enabled with the same amount of physical memory
Gain 37% memory capacity Handles 1700 simulated users

Max Partition throughput: 99 tps 12-core POWER7 partition 18 GB Memory
. 18 GB true 0 GB expanded

+ 65%

Max Partition Throughput: 166 tps 12-core POWER7 partition 24.7 GB Memory
18 GB true . 6.7 GB expanded

Expanded Memory
Note: This is an illustrative scenario based on using a sample workload. This data represents measured results in a controlled lab environment. Your results may vary.
� 2010 IBM Corporation

IBM Power Systems

Sample SAP ERP Workload, Enabled Additional Application Partition
Without Active Memory Expansion
System Utilization
Memory: 100% (48 GB) CPU: 76% on 24 cores 25% (8 core) unused

With Active Memory Expansion
System Utilization
Memory: 100% (48 GB) CPU: 94% on 32 cores
Note: Majority CPU increase is due to additional work.

Memory Capacity is the bottle-neck
CPU is under-utilized Handles 2900 simulated users Partitions have reached physical memory limitations by showing moderate paging

Higher throughput enabled
Enabled unused CPU resources (25% of server) with no add'l physical memory. Gain 30% in application server memory capacity Handles 5000 simulated users

System Throughput: 286 TPS

+ 60%

System Throughput: 460 TPS

3 x 8-core POWER7 partitions
48 GB true . 0 GB expanded
LPAR 2 (AppServer) LPAR 3 (AppServer) LPAR 1 (DB + App)

4 x 8-core POWER7 partitions
48 GB true . 14 GB expanded
LPAR 2 (AppServer) LPAR 3 (AppServer) LPAR 4 (AppServer) � 2010 IBM Corporation LPAR 1 (DB + App)

Note: This is an illustrative scenario based on using a sample workload. This data represents measured results in a controlled lab environment. Your results may vary.

LPAR 4 (IDLE)

IBM Power Systems

Active Memory Expansion - CPU & Performance

"no free lunch", but can be a really good deal
% CPU utilization for expansion

Amount of memory expansion

� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion - CPU & Performance
2 % CPU utilization for expansion Very resource effective 1
1 = Plenty of spare CPU resource available 2 = Constrained CPU resource � already running at significant utilization

Amount of memory expansion There is a knee-of-cure relationship for CPU resource required for memory expansion
Busy processor cores don't have resources to spare for expansion The more memory expansion done, the more CPU resource required

Knee varies depending on how compressible memory contents are
� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion � Deployment Steps
1
Planning Tool
A. Part of AIX 6.1 TL4 B. Calculates data compressibility & estimates CPU overhead due to Active Memory Expansion C. Provides initial recommendations
Estimated Results
CPU Utilization

2
60-Day Trial
A. One-time, no-charge temporarily enablement B. Config LPAR based on planning tool C. Use AIX tools to monitor Act Mem Exp environment D. Tune based on actual results
App. Performance

3
Deploy into Production
A. Permanently enable Active Memory Expansion B. Deploy workload into production C. Continue to monitor workload using AIX performance tools

Actual Results
Performance

CPU Utilization

Memory Expansion

Memory Expansion

Memory Expansion

Time

� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion Product Structure
One-time, 60-day trial - No charge
Request via Capacity on Demand Web page www.ibm.com/systems/power/hardware/cod/

Permanent Enablement - Chargeable
Power 750 #4792 Act Mem Exp Enablement Feature Power 770 & Power 780 #4791 Act Mem Exp Enablement Feature ONE feature per server � no matter how many partitions choose to use it

Note: Enablement does not mean function has to be used. Enablement allows Act Mem Exp to
be used on any or all of the AIX partitions selected by the client
� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion Decision Making
Start off with adequate true physical memory
Not all AIX 6.1 applications/data allow effective expansion Active Memory Expansion less effective when CPU utilization is high. Be sure to consider peak workloads.

Best use: Active Memory Expansion as a way to expand beyond physical memory limits Before using to reduce memory purchase, need to understand how well current and future application data compresses and how much processor resource available for memory expansion (compression/decompression)
Additional processor resource part of AIX 6.1 partition and requires licensing like any other active core

If unsure of your expansion value, consider purchasing true physical memory initially and then using Active Memory Expansion as a future MES order after analyzing its use.

� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion Economics
Three Scenarios
Scenario A: Server has maximum possible true memory and CPU utilization is relatively low. Memory limits constrain server from doing more work.
Active Memory Expansion is a "no brainer" with even modest memory expansion

Scenario B: Server is not at maximum true memory and CPU utilization relatively low. Choosing between adding more true memory and Act Mem Exp.
Calculate gained memory: true memory x expansion factor = gained memory. For example, 96 GB true memory with a 30% expansion = 29 GB gained. Compare cost of additional true memory versus cost of Active Memory Expansion. If costs are equal, then chose true memory. But if memory expansion offers savings, then order it with an appropriate amount of true memory. As appropriate, include additional software licensing, memory activations, processor activations in the analysis.

Scenario C: Server is full of smaller DIMMs, but more memory is needed. Removing smaller memory DIMMs and purchasing larger DIMMs not desirable.
Analysis same as to Scenario B. Need to project an expansion factor.

� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion - Planning Tool
Active Memory Expansion Modeled Statistics: ----------------------Modeled Expanded Memory Size : 8.00 GB Expansion Factor --------1.21 1.31 1.41 True Memory Modeled Size -------------6.75 GB 6.25 GB 5.75 GB

Modeled Gain ----------------1.25 GB [ 19%] 1.75 GB [ 28%] 2.25 GB [ 39%]

t utpu o ple Sam CPU Usage Memory
Estimate ----------0.00 0.20 0.35

This sample partition has fairly good expansion potential A nice "sweet" spot for this partition appears to be 45% expansion
� 2.5 GB gained memory � Using about 0.58 cores additional CPU resource

1.51
1.61

5.50 GB
5.00 GB

2.50 GB[ 45%]
3.00 GB [ 60%]

0.58
1.46

Active Memory Expansion Recommendation: --------------------The recommended AME configuration for this workload is to configure the LPAR with a memory size of 5.50 GB and to configure a memory expansion factor of 1.51. This will result in a memory expansion of 45% from the LPAR's current memory size. With this configuration, the estimated CPU usage due to Active Memory Expansion is approximately 0.58 physical processors, and the estimated overall peak CPU resource required for the LPAR is 3.72 physical processors.

Tool included in AIX 6.1 TL4 SP2 Run tool in the partition of interest for memory expansion. Input desired expanded memory size. Tool outputs different real memory and CPU resource combinations to achieve the desired effective memory.
� 2010 IBM Corporation

IBM Power Systems

Act Mem Exp � Turning a Partition On or Off
With HMC, check Active Memory Expansion box and enter true and max memory memory expansion factor To turn off expansion, unclick box Partition IPL required to turn on or off
5.5 true 8.0 max

Active Memory Expansion Modeled Statistics: ----------------------Modeled Expanded Memory Size : 8.00 GB Expansion Factor --------1.21 1.31 1.41 1.51 1.61 True Memory Modeled Size -------------6.75 GB 6.25 GB 5.75 GB 5.50 GB 5.00 GB

utput mple o Sa
CPU Usage Estimate ----------0.00 0.20 0.35 0.58 1.46

Modeled Memory Gain ----------------1.25 GB [ 19%] 1.75 GB [ 28%] 2.25 GB [ 39%] 2.50 GB [ 45%] 3.00 GB [ 60%]

Active Memory Expansion Recommendation: --------------------The recommended AME configuration for this workload is to configure the LPAR with a memory size of 5.50 GB and to configure a memory expansion factor of 1.51. This will result in a memory expansion of 45% from the LPAR's current memory size. With this configuration, the estimated CPU usage due to Active Memory Expansion is approximately 0.58 physical processors, and the estimated overall peak CPU resource required for the LPAR is 3.72 physical processors.

� 2010 IBM Corporation

IBM Power Systems

Act Mem Exp � Operations Considerations
� � � � Active Memory Expansion is transparent to applications A server using Active Memory Expansion needs an HMC on the server. Enabling Active Memory Expansion: does NOT require a server IPL Turning Active Memory Expansion on/off for a partition DOES require an IPL of that partition.
However, changing the expansion factor (leaving Active Memory Expansion "on") does NOT require an IPL. If you set expansion factor to 1.0 , it is effectively the same as memory expansion turned off... with one caveat, Active Memory Expansion uses the smaller memory page sizes, not some of the larger page sizes. For a small percentage of clients this page size may be a factor.

� Hardware & software requirements
POWER7 servers running in POWER7 mode (Power 750, 770, 780) HMC: V7R7.1.0.0 or later Firmware: 7.1 or later AIX 6.1 TL4 SP2 or later

� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion � Monitoring Capability
After Active Memory Expansion enabled and turned on ...
Single LPAR monitoring Live monitoring of metrics for a LPAR (compression ratio, number of compression ops, actual amount of CPU used for compression, amount of memory that is compressed Provides indication of actual memory expansion levels achieved System level monitoring (across multiple LPAR's) Live monitoring of expansion metrics for multiple LPAR's on a system Record metrics over time for archiving and historical analysis

Monitor Active Memory Expansion occasionally
to see how much CPU you are consuming for compression and to monitor whether the workload is compressing well enough to meet the memory expansion targets.

Monitoring tools provided as no-charge enhancements to existing performance tools already shipped with AIX and familiar to AIX administrators.
Examples: lparstat, vmstat, topas, svmon

Run as stand-alone utility Included with AIX 6.1 and TL4 SP2 at no additional charge
� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion - Documentation
AIX publications in Infocenter at http://publib.boulder.ibm.com/infocenter/aix/v6r1/index.jsp Sections/books with Active Memory Expansion content:
AIX Commands Reference Detailed information about the AIX commands/utilities/tools including various performance tools that support Active Memory Expansion Information on Active Memory Expansion planning tool (amepat) AIX Performance Management Guide Overview describing Active Memory Expansion and how to use it.

White papers
"Active Memory Expansion: Overview and Users Guide" by David Hepkin www.ibm.com/systems/power/resources/index.html (then click on white papers) or www.ibm.com/support/techdocs/atsmastr.nsf/Web/TechDocs "Active Memory Expansion: Performance Considerations" by Dirk Michel www.ibm.com/systems/power/resources/index.html (then click on white papers) or www.ibm.com/support/techdocs/atsmastr.nsf/Web/TechDocs

Movie on introduction, technology, use, installation, operation

(18 min)

www.ibm.com/developerworks/wikis/display/WikiPtype/Movies by Nigel Griffiths

� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion & Active Memory Sharing
Active Memory Expansion Effectively gives more memory capacity to the partition using compression / decompression of the contents in true memory AIX partitions only Active Memory Sharing Moves memory from one partition to another Best fit when one partition is not busy when another partition is busy AXI, IBM i, and Linux partitions
15 10 #10 #9 #8 #7 #6 #5 #4 #3 #2 #1

5

0

Active Memory Expansion

Active Memory Sharing

Supported, potentially a very nice option Considerations Only AIX partitions using Active Memory Expansion Active Memory Expansion value is dependent upon compressibility of data and available CPU resource
� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion � Miscellaneous
� If using Live Partition Mobility and if using Active Memory Expansion, both the "from" and the "to" servers must have Active Memory Expansion in place. � If a server gets really busy, memory expansion won't stop. It just means that the workload will slow down, just as it would if Act Mem Exp was not in-use and the workload maxed out the CPU. � You can use Active Memory Expansion in the shared processor pool if the server is enabled. Each partition in the pool turns Act Mem Exp on or off independently. Each partition's expansion factor is independent. � At the end of the 60-day trial period (assuming no permanent enablement), then:
no additional partitions can be enabled for memory expansion An existing partition already enabled for memory expansion may not be able to adjust its expansion value except to change it to 1.0 (no expansion) When an existing partition is rebooted, it loses memory expansion capability Note permanent memory expansion capability activation can be added dynamically before the end of the trial period. This preserves the existing partition's ability to use memory expansion without a reboot.

� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion Summary
Innovative POWER7 technology
For AIX 6.1 or later For POWER7 servers

Uses compression/decompression to effectively expand the true physical memory available for client workloads Often a small amount of processor resource provides a significant increase in the effective memory maximum
Processor resource part of AIX partition's resource and licensing

Actual expansion results dependent upon how "compressible" the data being used in the application
A SAP ERP sample workload shows up to 100% expansion, Your results will vary Estimator tool and free trial available

� 2010 IBM Corporation

IBM Power Systems

Active Memory Expansion
Effectively up to 100% more memory

True memory

True memory

True memory

Expand memory

Expand memory

Expand memory

True memory

True memory

True memory

Expand memory

Expand memory

Expand memory

POWER7 advantage Expand memory beyond physical limits More effective server consolidation
Run more application workload / users per partition Run more partitions and more workload per server

� 2010 IBM Corporation

IBM Power Systems

Special notices
This document was developed for IBM offerings in the United States as of the date of publication. IBM may not make these offerings available in other countries, and the information is subject to change without notice. Consult your local IBM business contact for information on the IBM offerings available in your area. Information in this document concerning non-IBM products was obtained from the suppliers of these products or other public sources. Questions on the capabilities of non-IBM products should be addressed to the suppliers of those products. IBM may have patents or pending patent applications covering subject matter in this document. The furnishing of this document does not give you any license to these patents. Send license inquires, in writing, to IBM Director of Licensing, IBM Corporation, New Castle Drive, Armonk, NY 10504-1785 USA. All statements regarding IBM future direction and intent are subject to change or withdrawal without notice, and represent goals and objectives only. The information contained in this document has not been submitted to any formal IBM test and is provided "AS IS" with no warranties or guarantees either expressed or implied. All examples cited or described in this document are presented as illustrations of the manner in which some IBM products can be used and the results that may be achieved. Actual environmental costs and performance characteristics will vary depending on individual client configurations and conditions. IBM Global Financing offerings are provided through IBM Credit Corporation in the United States and other IBM subsidiaries and divisions worldwide to qualified commercial and government clients. Rates are based on a client's credit rating, financing terms, offering type, equipment type and options, and may vary by country. Other restrictions may apply. Rates and offerings are subject to change, extension or withdrawal without notice. IBM is not responsible for printing errors in this document that result in pricing or information inaccuracies. All prices shown are IBM's United States suggested list prices and are subject to change without notice; reseller prices may vary. IBM hardware products are manufactured from new parts, or new and serviceable used parts. Regardless, our warranty terms apply. Any performance data contained in this document was determined in a controlled environment. Actual results may vary significantly and are dependent on many factors including system hardware configuration and software design and configuration. Some measurements quoted in this document may have been made on development-level systems. There is no guarantee these measurements will be the same on generallyavailable systems. Some measurements quoted in this document may have been estimated through extrapolation. Users of this document should verify the applicable data for their specific environment.

� 2010 IBM Corporation

IBM Power Systems

Special notices (cont.)
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