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Tuning z/OS UNIX performance in a sysplex z/OS UNIX System Services Planning GA32-0884-00 |
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The intersystem communication required to provide the additional availability and recoverability associated with z/OS UNIX shared file system support, affects response time and throughput on R/W file systems being shared in a sysplex. For example, assume that a user on SY1 requests a read on a file
system mounted R/W and owned by SY2. Using shared file system support,
SY1 sends a message requesting this read to SY2 via an XCF messaging
function:
After
SY2 gets this message, it issues the read on behalf of SY1, and gathers
the data from the file. It then returns the data via the same route
the request message took:
Thus, adding z/OS UNIX to a sysplex increases XCF message traffic. To control this traffic, closely monitor the number and size of message buffers and the number of message paths within the sysplex. It is likely that you will need to define additional XCF paths and increase the number of XCF message buffers above the minimum default. For more information on signaling services in a sysplex environment, see z/OS MVS Setting Up a Sysplex . Be aware that because of I/O operations to the CDS, every mount request requires additional system overhead. Mount time increases as a function of the number of mounts, the number of members in a sysplex, and the size of the CDS. You will need to consider the effect on your recovery time if a large number of mounts are required on any system participating in a shared file system. |
Copyright IBM Corporation 1990, 2014
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