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7. Recommendations from the joint IBM/SAP Platform Team:
Always use the latest z/VM release available , currently z/VM 5.3
Apply z/VM 5.1 APAR 63636 (PTF UM31312)
Apply all z/VM APARs listed in OSS Note 81737
Additional z/VM Considerations (these are specific to the customer configuration
and the workload characteristics) :
Consider HiperSockets , Vdisk, Vlan for network/swapping optimization
Consider workload distribution techniques such as add/reduce CPUs
dynamically as LPAR load changes and distribute workload over
day/night/weekend
Disable unused Linux guests to eliminate resource consumption (memory,
CPU)
Limit number of CPUs per Linux guest to reduce overhead cycles for
unused CPUs
Use FCP/SCSI devices instead of FICON/ECKD or ESCON to improve
throughput
Use Quick Dispatch for dialog intensive Linux guests to improve response
time
Review possible overcommitment of memory to avoid paging in z/VM
Apply the Fixed I/O Buffers Fix (SLES 9 SP1) available at
http://www.128.ibm.com/developerworks/linux/linux390/perf/tuning_rec_fixed_io_buffers.html
For additional fixes and tuning hints please see:
http://www.128.ibm.com/developerworks/linux/linux390/index.html
Use multiple swap volumes to avoid I/O bottlenecks.
Always use the latest available Linux kernel (currently SLES 10 SP1)
Configure swap volumes on the disk subsystem so that multiple channels are used.
If for example 15 of the 2.3 GB logical swap volumes are being mapped to a single
72 GB physical drive the throughput rate will be low.
FICON can support more swap volumes than channels. For example if you are
using 8 FICON channels then define 16-24 swap devices.
In Linux set the priority equal for all swap volumes.
Minimize paging and swapping.
Define the Linux guests as small as possible without
having Linux swapping occur on a regular basis.
If using extended memory for z/VM avoid paging in and out of extended memory.
Do not use z/VM TCP/IP as an IP router, this results in high CPU consumption.
Do not use MDC for SAP, this will conserve memory.
Tune the number of SAP work processes using SAP transaction SM50 or SM66.
For the HiperSocket definition to the DataBase LPAR use an MTU size of 16K or
larger.
Copyright 2006
IBM Solutions Technical Sales (STS) 12/18/2007Page 49 of 51
12/18/2007
Planning and Preparation Guide for SAP NetWeaver Version 6.40: z/OS Implementation