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

13Overview of CDS
CDS disk access and format
records created by the VxVM auto-configuration mode. Disk type auto
automatically determines which format is on the disk.
Platform block
The platform block resides on disk sector 0, and contains data specific to the
operating system for the platforms. It is necessary for proper interaction with
each of those platforms. The platform block allows a disk to perform as if it was
initialized by each of the specific platforms.
AIX coexistence label
The AIX coexistence label resides on the disk, and identifies the disk to the AIX
logical volume manager (LVM) as being controlled by VxVM.
HP-UX coexistence label
The HP-UX coexistence label resides on the disk, and identifies the disk to the
HP logical volume manager (LVM) as being controlled by VxVM.
VxVM ID block
The VxVM ID block resides on the disk, and indicates the disk is under VxVM
control. It provides dynamic VxVM private region location and other
information.
CDS disk groups
A CDS disk group allows cross-platform data sharing of VxVM objects, so that
data written on one of the supported platforms may be accessed on any other
supported platform. A CDS disk group is composed only of CDS disks (VM disks
with the disk format
cdsdisk), and is only available for disk group version 110
and greater.
Note: 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.
All VxVM objects in a CDS disk group are aligned and sized so that any system
can access the object using its own representation of an I/O block. The CDS disk
group uses a platform-independent alignment value to support system block
sizes of up to 8K.
See “Disk group alignment” on page 15.