IBM I5, I5/OS Recommendation, Main Storage size MUST be carefully planned !, Remember

iSeries. mySeries.
Main Storage Concepts
Memory Allocation Facts
A “Hardware Page Table(HPT)” is needed to manage memory
Power4 Hypervisor reserved HPT within partition memory
Power5 Hypervisor allocates HPT separately from partition memory
Size of the HPT depends of the maximum memory amount the partition can receive
Basic calculation : maximum memory divided by 64, rounded up to next power of 2
A partition can allocates a maximum of 12 GB (12288 MB)
HPT size will be 12288 / 64 = 192 ... next power of 2 is ... 256
HPT size will be 256 MB
Recommendation
Takecare of HPT when allocating memory to partitions !
Plan to allocate 12288 - 256 = 12032 MB for the partition
Memory actually used will be 12288 MB
Main Storage size MUST be carefully planned !
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iSeries. mySeries.
Main Storage Concepts
Memory Allocation Facts
Remember
A node is a packaged set of processors, caches (L1+L2+L3) and memory on a module
Remember about ... “home node”,“local node” and “remote node” ?
Remember about ... “local memory access” and “remote memory access”
Remember about ... “memory affinity” ?
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