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

15Overview of CDS
Non-CDS disk groups
Minor device numbers
Importing a disk group will fail if it will exceed the maximum devices for that
platform.
Note: There is a large disparity between the maximum number of devices
allowed for devices on the Linux platform with a pre-2.6 kernel, and that for
other supported platforms.
Non-CDS disk groups
Any version 110 (or greater) disk group (DG) can contain both CDS and non-CDS
disks. However, only version 110 (or greater) disk groups composed entirely of
CDS disks have the ability to be shared across platforms. Whether or not that
ability has been enabled is a controlled by the cds attribute of the disk group.
Enabling this attribute causes a non-CDS disk group to become a CDS disk
group.
Although a non-CDS disk group can contain a mixture of CDS and non-CDS disks
having dissimilar private region alignment characteristics, its disk group
alignment will still direct how all subdisks are created.
Disk group alignment
One of the attributes of the disk group is the block alignment, which represents
the largest block size supported by the disk group.
The alignment constrains the following attributes of the objects within a disk
group:
■ Subdisk offset
■ Subdisk length
■ Plex offset
■ Volume length
■ Log length
■ Stripe width
The offset value specifies how an object is positioned on a drive.
The disk group alignment is assigned at disk group creation time.
See “Disk group tasks” on page 29.