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.
The following
parameters include considerations for selecting and configuring the
hardware on which the application servers run.
Procedure
- 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
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 i5/OS, processing power can be related to the Commercial
Processing Workload (CPW) value of the system. For more information
about CPW values, see the http://www.ibm.com/servers/eserver/iseries/perfmgmt/resource.html Web site.
- 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 i5/OS
command line. For information about the minimum memory requirements,
see the IBM Support Web site.
- 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 Web sites 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.
- Real storage minimum is 512 MB per LPAR for a light load such
as the IVP. For most real-world applications, we recommend 2 GB or
higher. We have seen applications that require as much as 8 GB of
real to operate at peak load.
DASD
- Recommendation
- To maximize your performance, we recommend a fast DASD subsystem
(for example, IBM Shark), running with a high cache read/write hit
rate.
Networking
- Recommendation
- For high bandwidth applications, we recommend at least a 1 Gb
Ethernet connection. If your applications have extremely high bandwidth
requirements, you may need additional Ethernet connections.