IBM eServer zSeries 900 Technical Guide

56 IBM eServer zSeries 900 Technical Guide

2.5.5 LPAR Dynamic Storage Reconfiguration

Dynamic Storage Reconfiguration (DSR) on z900 servers allows an operating system running

in a logical partition to add nondisruptively its reserved storage amount to its configuration, if

any unused storage exists. This unused storage can be obtained when another logical

partition releases some storage, or when a concurrent memory upgrade takes place.

With enhanced DSR, the unused storage does not have to be continuous.

When an operating system running in a logical partition assigns a storage increment to its

configuration, LPAR will check if there are any free storage increments and will dynamically

bring the storage online.

LPAR will dynamically take offline a storage increment and will make it available to other

partitions when an operating system running in a logical partition releases a storage

increment.

2.6 Channel Subsystem

The z900 Channel Subsystem (CSS) design provides great flexibility, and high availability and

performance, allowing:

򐂰 High bandwidth

The z900 CSS can handle up to 24 GB/s, which is three times the 9672 G6 server’s

bandwidth. Individual channels can have up to 2 Gb/s data rates.

򐂰 Wide connectivity

A z900 server can be connected to an extensive range of interfaces, using protocols such

as Fibre Channel Protocol (FCP) for Small Computer System Interface (SCSI), Gigabit

Ethernet (GbE), Fast Ethernet (FENET), Asynchronous Transfer Mode (ATM) and High

Speed Token Ring, along with FICON, ESCON, parallel and coupling links channels.

򐂰 Concurrent channel upgrades

It is possible to concurrently add channels to a z900 server provided there are unused

channel positions in an I/O cage. Additional I/O cages can be previously installed on an

initial configuration, via CUoD, to provide greater capacity for concurrent upgrades. This

capability may help eliminate an outage to upgrade the channel configuration. See more

information about concurrent upgrades in 6.1, “Concurrent upgrades” on page 206.

򐂰 Dynamic I/O configuration

Dynamic I/O configuration enhances system availability by supporting the dynamic

addition, removal, or modification of channel paths, control units, I/O devices, and I/O

configuration definitions to both hardware and software (if it has this support) without

requiring a planned outage. Dynamic I/O configuration is

not available on the coupling

facility model.

򐂰 ESCON port sparing and upgrading

The ESCON 16-port I/O card includes one unused port dedicated for sparing in the event

of a port failure on that card. Other unused ports are available for growth of ESCON

channels without requiring new hardware, enabling concurrent upgrades via Licensed

Internal Code.