VERITAS Storage Foundation 4.1 Cross-Platform Data Sharing Administrator's Guide

Chapter 1, Overview
CDS Disk Access and Format
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AIX Coexistence Label
The AIX Coexistence label resides on the disk, and identifies the disk to the AIX 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 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 “Setting up Your System” on page 11 for more details.
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 7 for details.
CDS disk groups can be:
◆ Initialized on one system and then used “as-is” by VxVM on a system employing a different
type of platform.
◆ Imported (in a serial fashion) by Linux, Solaris, AIX, and HP-UX systems.
◆ Private, shared, or distributed (SAN VM).
◆ Shared by CVM.
You cannot include the following disks or volumes in a CDS disk group:
◆ Volumes of usage type root and swap. (This means that you cannot use CDS to share boot
devices.)