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Changing the VGID of rootvg and PVIDs of rootvg disks with ghostdev

Question & Answer


Question

How can I change rootvg's VGID and the PVIDs of the rootvg disks?

Answer

The physical volume identifier (PVID) and the volume group identifier (VGID) of the rootvg volume group can be changed during the system boot phase by setting the ghostdev attribute of the sys0 device to a value of 2 and rebooting the system.  This process is useful for booting a SAN bitwise copy or clone of rootvg.

To list the current ghostdev attribute, enter the following command:

# lsattr -El sys0 -a ghostdev

To set the ghostdev attribute, enter the following command:

# chdev -l sys0 -a ghostdev=2


The following are the available values for the ghostdev attribute:
  • ghostdev=0 is the default and changes nothing during reboot.
  • ghostdev=1 clears the customized ODM database on rootvg when AIX detects it booted from a different LPAR or system.
  • ghostdev=2 changes the VGID of rootvg and the PVIDs of rootvg disks on the next reboot.  It will also clear the customized ODM if booted on a different LPAR (same behavior as ghostdev=1).
  • ghostdev=3 skips reading all disks during ipl_varyon when some rootvg disks are unreadable.
    During boot time, ipl_varyon attempts to read every disk in rootvg.  If any of the reads fail, it reads every disk visible to the LPAR looking for a valid rootvg disk. These read operations can cause boot to take considerable time, especially when the system has many disks that take some time to complete the read.  With the ghostdev attribute set to 3, ipl_varyon skips the step of reading of all the disks in the system.  This setting can cause ipl_valyon to fail in finding a suitable disk to boot from in some cases.  Setting ghostdev=3 is an exclusive option and cannot be used with other ghostdev values.                                

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Document Information

Modified date:
11 January 2023

UID

isg3T1020387

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