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

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A logical volume <strong>on</strong> the Virtual I/O Server used as a virtual SCSI disk cannot<br />

exceed 1 TB in size.<br />

The SCSI protocol defines mandatory and opti<strong>on</strong>al commands. While virtual<br />

SCSI supports all the mandatory commands, not all opti<strong>on</strong>al commands are<br />

supported.<br />

Important: Although logical volumes that span multiple physical volumes are<br />

supported, for optimum performance, a logical volume should reside wholly <strong>on</strong><br />

a single physical volume. To guarantee this, volume groups can be composed<br />

of single physical volumes.<br />

Keeping an exported storage pool backing device or logical volume <strong>on</strong> a single<br />

hdisk results in optimized performance.<br />

Bad Block Relocati<strong>on</strong> <strong>on</strong> Virtual I/O Server Versi<strong>on</strong> 1.3 is supported as l<strong>on</strong>g as<br />

a virtual SCSI device is not striped, mirrored, and when the LV spans multiple<br />

PV.<br />

To verify that a logical volume does not span multiple disks, run the following:<br />

$ lslv -pv app_vg<br />

app_vg:N/A<br />

PV COPIES IN BAND DISTRIBUTION<br />

hdisk5 320:000:000 99% 000:319:001:000:000<br />

Only <strong>on</strong>e disk should appear in the resulting list.<br />

Installati<strong>on</strong> and migrati<strong>on</strong> c<strong>on</strong>siderati<strong>on</strong>s<br />

The following are the major installati<strong>on</strong> and migrati<strong>on</strong> c<strong>on</strong>siderati<strong>on</strong>s:<br />

►<br />

►<br />

►<br />

Planning client partiti<strong>on</strong> root volume group sizes prior to creating logical<br />

volumes is recommended. Increasing a rootvg by extending its associated<br />

Virtual I/O Server logical volume is not supported. For informati<strong>on</strong> about<br />

extending volume groups, see “Increasing a client partiti<strong>on</strong> volume group” <strong>on</strong><br />

page 311.<br />

Migrating from a physical SCSI disk to a virtual SCSI device is not supported<br />

at this time. All virtual SCSI devices created <strong>on</strong> the Virtual I/O Server are<br />

treated as new devices. A backup and restore of the data would be required<br />

when migrating from a physical device to a virtual device.<br />

The Virtual I/O Server uses several methods to uniquely tag a disk for use in<br />

as a virtual SCSI disk. They are:<br />

– Unique device identifier (UDID)<br />

– IEEE volume identifier<br />

100 <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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