A VM disk usually has a private and a public region.

The private region is a small area on the disk where VxVM configuration information is stored, such as a disk header label, configuration records for VxVM objects (such as volumes, plexes and subdisks), and an intent log for the configuration database. The default private region size is 32MB, which is large enough to record the details of several thousand VxVM objects in a disk group.

The public region covers the remainder of the disk, and is used for the allocation of storage space to subdisks.

The private and public regions are aligned and sized in multiples of 8K to permit the operation of CDS. The alignment of VxVM objects within the public region is controlled by the disk group alignment attribute. The value of the disk group alignment attribute must also be 8k to permit the operation of CDS.