Use these tips to tune your z/OS® operating system to optimize WebSphere® Application Server performance.
WebSphere Application Server for z/OS no longer requires or recommends the shared file system for the configuration files, since it maintains its own mechanism for managing this data in a cluster. However, WebSphere for z/OS does require the shared files system for XA partner logs. Your application may also use the shared file system. This article provides some basic tuning information for the shared file system.
For basic z/OS UNIX® System Services performance information, refer to the following website: http://www.ibm.com/servers/eserver/zseries/ebusiness/perform.html
Special consideration needs to be made to file system access when you run in a sysplex. If you mount the file system R/W in a shared file system environment, only one system will have local access to the files. All other systems have remote access to the files which negatively affects performance. You may choose to put all of the files for WebSphere in their own mountable file system and mount it R/O to improve performance. However, to change your current application or install new applications, the file system must be mounted R/W. You will need to put operational procedures in place to ensure that the file system is mounted R/W when updating or installing applications.
HFS Files Caching Read/Write files are cached in kernel data spaces. In order to determine what files would be good candidates for file caching you can use SMF 92 records.
Initial cache size is defined in BPXPRMxx.
z/OS has introduced a new file system called zFS which should provide improved file system access. You may benefit from using the zFS for your UNIX file system. See z/OS UNIX System Services Planning for more information.
High activity, read-only files can be cached in the USS kernel using the filecache command. Access to files in the filecache can be much more efficient than access to files in the shared file system, even if the shared file system files are cached in dataspaces. GRS latch contention, which sometimes is an issue for frequently accessed files shared file system, will not affect files in the filecache.
To filecache important files at startup, you can add filecache command to your /etc/rc file. Unfortunately, files which are modified after being added to the filecache may not be eligible for caching until the file system is unmounted and remounted, or until the system is re-IPLed. Refer to z/OS UNIX System Services Command Reference for more information about the filecache command.
/usr/sbin/filecache -a /usr/lpp/WebSphere/V5R0M0/ MQSeries/java/samples/base/de_DE/mqsample.html