Restrictions on using rootability with Linux

Bootable root disks with msdos disk labels can contain up to four primary partitions: /dev/sdx1 through /dev/sdx4 for SCSI disks, and /dev/hdx1 through /dev/hdx4 for IDE disks. If more than four partitions are required, a primary partition can be configured as an extended partition that contains up to 11 logical partitions (/dev/sdx5 through/dev/sdx15) for SCSI disks and 12 logical partitions (/dev/hdx5 through/dev/sdx16) for IDE disks.


Extensible Firmware Interface (EFI) disks with GUID Partition Table (GPT) labels are not supported for root encapsulation.

To encapsulate a root disk, VxVM requires one unused primary partition entry to represent the public region, plus one unused primary partition or one unused logical partition for the private region.

The entry in the partition table for the public region does not require any additional space on the disk. Instead it is used to represent (or encapsulate) the disk space that is used by the existing partitions.

Unlike the public region, the partition for the private region requires a relatively small amount of disk space. By default, the space required for the private region is 32MB, which is rounded up to the nearest whole number of cylinders. On most modern disks, one cylinder is usually sufficient.

To summarize, the requirements for the partition layout of a root disk that can be encapsulated are:

The following error message is displayed by the vxencap or vxdiskadm commands if you attempt to encapsulate a root disk that does not have the required layout:

    Cannot find appropriate partition layout to allocate space
    for VxVM public/private partitions.

The following sections show examples of root disk layouts for which encapsulation is either supported or not supported.

Note the following additional important restrictions on using rootability with Linux:

More Information

Example 1: unsupported root disk layouts for encapsulation