An optimal hardware configuration enables applications
to get the greatest benefit from performance tuning. The hardware
speed impacts all types of applications and is critical to overall
performance.
About this task
For proper system sizing for WebSphere® Application Server
workloads, use the IBM® Systems
Workload Estimator.
You can check hardware configuration
and settings such as disk speed, system memory and processor speed
to gain performance benefits.
Procedure
- Use the following considerations for selecting and configuring
the hardware on which the application servers run:
- Optimize disk speed
- Description: Disk speed and the number of disk arms have a significant
effect on application server performance in the following cases:
- Your application is heavily dependent on database support .
- Your application uses messaging extensively.
- Recommendation: Use disk I/O subsystems that are optimized for
performance, for example, Redundant Array of Independent Disks (RAID).
Distribute the disk processing across as many disks as possible to
avoid contention issues that occur with 1 or 2 disk systems. For more
information about disk arms and how they can affect performance, see
the iSeries® Disk Arm Requirements documentation.
- Increase processor speed and processor cache
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Description: In
the absence of other bottlenecks, increasing the processor speed often
helps throughput and response times. A processor with a larger L2
or L3 cache yields higher throughput, even if the processor speed
is the same as a CPU with a smaller L2 or L3 cache.
Description: In
the absence of other bottlenecks, increasing the processing power
can improve throughput, response times, or both. On WebSphere Application Server for IBM i, processing power can be related
to the Commercial Processing Workload (CPW) value of the system. For
more information about CPW values, see the Performance Management website.
- Increase system memory
- Description: Increase memory to prevent the system from paging
memory to the disk to improve performance. Allow a minimum of 256
MB of memory for each processor and 512 MB per application server.
Adjust the available memory when the system pages and the processor
utilization is low because of the paging. The memory access speed
might depend on the number and placement of the memory modules. Check
the hardware manual to make sure that your configuration is optimal.
- Recommendation: Use 256 MB of memory for each processor and 512
MB per application server. Some applications might require more memory.
- Description: If a large number of page faults occur, performing
the following tasks to improve performance:
- Increase the memory available to WebSphere Application Server.
- Move WebSphere Application
Server to another memory pool.
- Remove jobs from the WebSphere Application
Server memory pool
- Recommendation: To determine the current page fault level, run
the Work with System Status (WRKSYSSTS) command from an IBM i command line. For information about the
minimum memory requirements, see the IBM Support website.
- Increase system memory
- Description: Increase memory to prevent the system from paging
memory to the disk to improve performance. Allow a minimum of 256
MB of memory for each processor and 512 MB per application server.
Adjust the available memory when the system pages and the processor
utilization is low because of the paging. The memory access speed
might depend on the number and placement of the memory modules. Check
the hardware manual to make sure that your configuration is optimal.
- Recommendation: Use 256 MB of memory for each processor and 512
MB per application server. Some applications might require more memory.
- Description: The amount of storage required for z/OS is mostly dependent on the number of servers
and the size of the Java Virtual
Machine (JVM) heap for each server.
- Recommendation: For a single server with 1 GB JVM heap, allocate
a minimum of 1GB of memory.
- Description: Increase memory to prevent the system from paging
memory to the disk to improve performance. Allow a minimum of 256
MB of memory for each processor and 512 MB per application server.
Adjust the available memory when the system pages and the processor
utilization is low because of the paging. The memory access speed
might depend on the number and placement of the memory modules. Check
the hardware manual to make sure that your configuration is optimal.
- Recommendation: Use 256 MB of memory for each processor and 512
MB per application server. Some applications might require more memory.
- Description: If a large number of page faults occur, performing
the following tasks to improve performance:
- Increase the memory available to WebSphere Application Server.
- Move WebSphere Application
Server to another memory pool.
- Remove jobs from the WebSphere Application
Server memory pool
- Recommendation: To determine the current page fault level, run
the Work with System Status (WRKSYSSTS) command from an IBM i command line. For information about the
minimum memory requirements, see the IBM Support website.
- Run network cards and network switches at full duplex
- Description: Run network cards and network switches at full duplex
and use the highest supported speed. Full duplex is much faster than
half duplex. Verify that the network speed of adapters, cables, switches,
and other devices can accommodate the required throughput. Some websites
might require multiple gigabit links.
- Recommendation Make sure that the highest speed is in use on 10/100/1000
Ethernet networks.
Verify that the
activity levels for storage pools are sufficient - Description: Verify that the activity levels for storage pools
are sufficient. Increasing these values can prevent threads from transitioning
into the ineligible condition.
- Recommendation
An IBM S/390® or zSeries® Model that supports
the software requirement of z/OS V1R2.
Storage - Storage requirements are higher than for traditional workloads
- Recommendation
- Virtual storage default should be about 370 MB per servant, which
includes a 256 MB default heap size and a default initial LE heap
size of 80 MB.
Best practice: Real storage minimum is 512
MB per LPAR for a light load such as the IVP. For most real-world
applications, you should use 2 GB or higher. We have seen applications
that require as much as 8 GB of real to operate at peak load.
bprac
DASD - Recommendation
Best practice: To maximize your performance,
you should use a fast DASD subsystem (for example, IBM Shark), running with a high cache read/write
hit rate.
bprac
Networking - Recommendation
Best practice: For high bandwidth applications,
you should use at least a 1 Gb Ethernet connection. If your applications
have extremely high bandwidth requirements, you may need additional
Ethernet connections.
bprac
Cryptography - Recommendation
Note: For applications that make heavy use of cryptography, you
should use the zSeries or S/390 cryptographic hardware and
the Integrated Cryptographic Service Facility. For more information,
refer to the
zSeries and S/390 Cryptography website.