Veritas Storage Foundation 5.1 SP1 Advanced Features Administrator"s Guide (5900-1503, April 2011)

You can limit the number of devices that can be created in a given CDS disk group
by setting the device quota.
See “Setting the maximum number of devices for CDS disk groups” on page 478.
When you create a device, an error is returned if the number of devices would
exceed the device quota. You then either need to increase the quota, or remove
some objects using device numbers, before the device can be created.
See “Displaying the maximum number of devices in a CDS disk group” on page 482.
Note: The default device quota for HP-UX is 32767.
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 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
461Migrating data between platforms
CDS disk format and disk groups