IBM Z9, Planning Manual

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HSA Allocation
This section addresses hardware system area (HSA) allocation.
HSA Estimation Tool
The HSA Estimation Tool, available on Resource Link at http://www.ibm.com/
servers/resourcelink , estimates the HSA size for the specified configuration and
product.
The HSA allocation can vary according to the I/O configuration. The following
system I/O configurations require the given HSA size on a z9 EC.
v Small system I/O configuration (S08): 1344 MB
– 1 CSS
– 2 LPs
– 96 physical control units
– 4096 devices
– 64 channels defined in the IOCDS
– Dynamic I/O configuration not enabled
– Concurrent code change not authorized
v Large system I/O configuration (S38): 4288 MB
– 4 CSSs
– 60 LPs
– 65280 devices per LCSS for subchannel set 0
– 65535 devices per LCSS for subchannel set 1
– Dynamic I/O configuration enabled
– Concurrent code change authorized
Intermediate HSA sizes exist for configuration sizes in between the given small and
large I/O configuration examples.
The HSA range for the z9 BC is approximately 1-2 GB.
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PR/SM Planning Guide