LPAR CPU Management
LPAR CPU Management allows WLM working in goal mode to manage the processor weighting and logical processors across an LPAR cluster. CPU resources are automatically moved toward LPARs with the greatest need by adjusting the partition’s weight. WLM also manages the available processors by adjusting the number of logi- cal CPs in each LPAR. This helps optimize the processor speed and multiprogramming level for each workload, helps reduce MP overhead, and helps give z/OS more control over how CP resources are distributed to help meet your business goals.
z/OS 1.2 enhances the LPAR CPU management capa- bilities and will allow the dynamic assignment of CPU resources to
Dynamic Channel Path Management
In the past, and on other architectures, I/O paths are
defi ned with a fi xed relationship between processors and devices. With z/OS and the zSeries, paths may be dynami- cally assigned to control units to refl ect the I/O load. For example, in an environment where an installation normally requires four channels to several control units, but occa- sionally needs as many as six, system programmers must currently defi ne all six channels to each control unit that may require them. With Dynamic Channel Path Manage- ment (DCM), the system programmer need only defi ne the four channels to the control units, and indicate that DCM may add an additional two. As the control unit becomes more heavily used, DCM may assign channels from a pool of managed channels, identifi ed by the system program- mer, to the control unit. If the work shifts to other control
units, DCM will unassign them from lesser utilized control units and assign them to what are now the more heavily used ones. DCM is for ESCON and FICON Bridge chan- nels and can help reduce the number of channels required to effectively run a workload. DCM can also help reduce the cost of the fi ber infrastructure required for connectiv- ity between multiple data centers. On a z990 with Logical Channel SubSystems (LCSSs), the scope of DCM man- agement is within a Logical Channel SubSystem. Although an LPAR cluster can span LCSSs, when DCM is used it will only consider systems in the same LPAR cluster and the same LCSS.
Channel Subsystem Priority Queuing
The notion of I/O Priority Queuing is not new; it has been in place in OS/390 for many years. With IRD, this capability is extended into the I/O channel subsystem. Now, when higher priority workloads are running in an LPAR cluster, their I/Os will be given higher priority and will be sent to the attached I/O devices (normally disk but also tape and network devices) ahead of I/O for lower priority workloads. LPAR priorities are managed by WLM in goal mode.
Channel Subsystem Priority Queuing provides two advan- tages. First, customers who did not share I/O connectivity via MIF (Multiple Image Facility) out of concern that a lower priority I/O intensive workload might preempt the I/O of higher priority workloads, can now share the channels and reduce costs. Second, high priority workloads may even benefi t with improved performance if there were I/O con- tention with lower priority workloads. Initially, Channel Sub- system Priority Queuing is implemented for Parallel OEMI and ESCON, FICON Bridge and native FICON channels.
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