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Advanced POWER Virtualization on IBM System p5 - Previous ...

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The <str<strong>on</strong>g>POWER</str<strong>on</strong>g> Hypervisor is part of all <strong>IBM</strong> <strong>System</strong> <strong>p5</strong> servers; you cannot<br />

c<strong>on</strong>figure a server without the <str<strong>on</strong>g>POWER</str<strong>on</strong>g> Hypervisor. All the performance<br />

benchmarks published by <strong>IBM</strong> <strong>on</strong> <strong>System</strong> <strong>p5</strong> servers are d<strong>on</strong>e with the <str<strong>on</strong>g>POWER</str<strong>on</strong>g><br />

Hypervisor. When you select an server with a given rPerf, this is the performance<br />

potential that is available for your applicati<strong>on</strong>s.<br />

5.6.1 Partiti<strong>on</strong> c<strong>on</strong>figurati<strong>on</strong> c<strong>on</strong>siderati<strong>on</strong>s<br />

This secti<strong>on</strong> describes some of the points to c<strong>on</strong>sider when c<strong>on</strong>figuring partiti<strong>on</strong>s<br />

<strong>on</strong> an <strong>IBM</strong> <strong>System</strong> <strong>p5</strong> server.<br />

Partiti<strong>on</strong> count<br />

As a general rule, the number of partiti<strong>on</strong>s should be kept as low as possible. It is<br />

preferable to c<strong>on</strong>solidate several applicati<strong>on</strong>s <strong>on</strong> to a single AIX 5L partiti<strong>on</strong><br />

rather than creating <strong>on</strong>e partiti<strong>on</strong> for each applicati<strong>on</strong>. This is sometimes not<br />

feasible for technical or organizati<strong>on</strong>al reas<strong>on</strong>s, for example, tuning AIX 5L for<br />

transacti<strong>on</strong>al database applicati<strong>on</strong>s may degrade performance in other types of<br />

applicati<strong>on</strong>s.<br />

Each partiti<strong>on</strong> must be managed just like any stand-al<strong>on</strong>e server, requiring<br />

c<strong>on</strong>figurati<strong>on</strong>, backups, and software licenses. Keeping the partiti<strong>on</strong> count down<br />

has a direct impact <strong>on</strong> the administrati<strong>on</strong> costs and thus <strong>on</strong> the total cost of<br />

ownership of any server.<br />

Further, each partiti<strong>on</strong> has associated resources. These resources have a<br />

c<strong>on</strong>text informati<strong>on</strong> that must be managed by the virtualizati<strong>on</strong> software. This<br />

management of state informati<strong>on</strong> c<strong>on</strong>sumes resources that might otherwise be<br />

deployed in the partiti<strong>on</strong>s.<br />

Resource maximums<br />

One parameter of partiti<strong>on</strong> definiti<strong>on</strong> is the maximum number of any given<br />

resource, be it memory, processors, or virtual I/O slots. It may be tempting to<br />

positi<strong>on</strong> the maximum values of these figures to be sure that it will always be<br />

possible to increase a partiti<strong>on</strong>’s resources using dynamic rec<strong>on</strong>figurati<strong>on</strong>.<br />

However, the <str<strong>on</strong>g>POWER</str<strong>on</strong>g> Hypervisor, just like an operating system, must maintain<br />

data structures that will allow it to manage the eventuality that each partiti<strong>on</strong><br />

receives the maximum possible resources. The Hypervisor will reserve the<br />

necessary memory making it unavailable to the partiti<strong>on</strong>s. You should therefore<br />

specify <strong>on</strong>ly realistic values for the maximum number of resources, using a<br />

planned margin.<br />

Virtual CPU count<br />

Related to the resource maximums is the virtual CPU count for any partiti<strong>on</strong> and<br />

the sum of all virtual processors in all the shared-processor partiti<strong>on</strong>s.<br />

356 <str<strong>on</strong>g>Advanced</str<strong>on</strong>g> <str<strong>on</strong>g>POWER</str<strong>on</strong>g> <str<strong>on</strong>g>Virtualizati<strong>on</strong></str<strong>on</strong>g> <strong>on</strong> <strong>IBM</strong> <strong>System</strong> <strong>p5</strong>

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