Encapsulation converts existing partitions on a specified disk to volumes. If any partitions contain file systems, their
/etc/fstab entries are modified so the file systems are mounted on volumes instead.
Disk encapsulation requires that enough free space be available on the disk (by default, 1 megabyte) for storing the private region that VxVM uses for disk identification and configuration information. This free space cannot be included in any other partitions.
vxencap(1M) manual page.
You can encapsulate a disk that does not have space available for the VxVM private region partition by using the
vxdisk utility. This is done by configuring the disk as a
nopriv devices that does not have a private region.
The drawback with using
nopriv devices is that VxVM cannot track changes in the address or controller of the disk. Normally, VxVM uses identifying information stored in the private region on the physical disk to track changes in the location of a physical disk. Because
nopriv devices do not have private regions and have no identifying information stored on the physical disk, tracking cannot occur.
One use of
nopriv devices is to encapsulate a disk so that you can use VxVM to move data off the disk. When space has been made available on the disk, remove the
nopriv device, and encapsulate the disk as a standard disk device.
A disk group cannot be formed entirely from
nopriv devices. This is because
nopriv devices do not provide space for storing disk group configuration information. Configuration information must be stored on at least one disk in the disk group.
To create a nopriv disk for encapsulation
vxdisk define partition-device
where partition-device is the basename of the device in the
/dev directory. For example, to map partition
3 of disk device
sdc, use the following command:
vxdisk define sdc3 type=nopriv
To create volumes for other partitions on a nopriv disk
vxassistto create a volume with the required length.