Intel 170 Servers, AS/400 RISC Server manual Linux on iSeries and IBM eServer Workload Estimator

typically recommended because it allows the Linux partitions to leverage the storage subsystem the customer has in the OS/400 hosting partition.

2.As the application gains in complexity, it is probably less likely that the application should switch from one product to the other. Such applications tend to implicitly play to particular design choices of their current product and there is probably not much to gain from moving them between products.

3.As scalability requirements grow beyond a 4-way, the DB2 on OS/400 product provides proven scalability that Linux may not match at this time. If functional requirements of the application require DB2 UDB on Linux and scaling beyond 4 processors, then a partitioned data base and multiple LPARs should be explored.

See also the IBM eServer Workload Estimator for sizing information and further considerations when adding the DB2 UDB for Linux on iSeries workload to your environment.

13.8 Linux on iSeries and IBM eServer Workload Estimator

At this writing, the Workload Estimator contains the following workloads for Linux on iSeries:

yFile Serving

yWeb Serving

yNetwork Infrastructure (Firewall, DNS/DHCP)

yLinux DB2 UDB

These contain estimators for the above popular applications, helpful for estimating system requirements. Consult the latest version of Workload Estimator, including its on-line help text, when specifying a system containing relevant Linux partitions. The workload estimator can be accessed from a web browser at http://www-912.ibm.com/wle/EstimatorServlet.

13.9 Top Tips for Linux on iSeries Performance

Here's a summary of top tips for improving your Linux on iSeries LPAR performance:

yKeep up to date on OS/400 PTFs for your hosting partition. This is a traditional, but still useful recommendation. So far, some substantial performance improvements have been delivered in fixes for Virtual LAN and Virtual Disk in particular.

yInvestigate keeping up to date with your distribution's kernel. Since these are not offered by IBM, this document cannot make any claims whatever about the value of upgrading the kernel provided by your Linux distributor. That said, it may be worth your while to investigate and see if any kernel updates are provided and whether you, yourself can determine if they aid your performance.

yIf possible, compare your Distribution's versions. This is a topic well beyond this paper in any detail, but in practice fairly simple. A Linux distributor might offer several versions of Linux at any given moment. Usually, you will wish the latest version, as it should be the fastest. But, if you can

IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
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