Veritas Storage Foundation Cross-Platform Data Sharing 5.0 AdministratorÆs Guide, HP-UX 11i v3, First Edition, May 2008

12 Overview of CDS
CDS disk access and format
■ Cannot contain a volume whose use-type is either root or swap (for
example, it cannot be a boot disk)
The CDS conversion utility, vxcdsconvert, is provided to convert non-CDS VM
disk formats to CDS disks, and disk groups with a version number less than 110
to disk groups that support CDS disks.
See “Converting non-CDS disks to CDS disks” on page 22.
CDS disk types
The CDS disk format, cdsdisk, is recognized by all VxVM platforms (including
Windows). The cdsdisk disk format is the default for all newly-created VM
disks unless overridden in a defaults file. The
vxcdsconvert utility is provided
to convert other disk formats and types to CDS.
See “Defaults files” on page 25.
Note: Disks with format cdsdisk can only be added to disk groups with version
110 or later.
Private and public regions
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.
Note: With other (non-CDS) VxVM disk formats, the private and public regions
are aligned to the platform-specific OS block size.
Disk access type auto
The disk access (DA) disk type auto supports multiple disk formats, including
cdsdisk, which is supported across all platforms. It is associated with the DA