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

In a version 110 disk group, a version 20 DCO volume has the following region
requirements:
■ Minimum region size of 16K
■ Incremental region size of 8K
Note: The map layout within a Data Change Object (DCO) volume changed with
the release of VxVM 4.0 to version 20. This can accommodate both FastResync
and DRL maps within the DCO volume. The original version 0 layout for DCO
volumes only accommodates FastResync maps.
Object alignment during volume creation
For CDS disk groups, VxVM objects that are used in volume creation are
automatically aligned to 8K. For non-CDS disk groups, the vxassist attribute,
dgalign_checking, controls how the command handles attributes that are subject
to disk group alignment restrictions. If set to strict, the volume length and values
of attributes must be integer multiples of the disk group alignment value, or the
command fails and an error message is displayed. If set to round (default), attribute
values are rounded up as required. If this attribute is not specified on the
command-line or in a defaults file, the default value of round is used.
The diskalign and nodiskalign attributes of vxassist, which control whether
subdisks are aligned on cylinder boundaries, is honored only for non-CDS disk
groups whose alignment value is set to 1.
Setting up your system
In order to migrate data between platforms using CDS, set up your system to use
CDS disks and CDS disk groups. The CDS license must be enabled. You can use
the default files to configure the appropriate settings for CDS disks and disk
groups.
Table 28-1 describes the tasks for setting up your system to use CDS.
463Migrating data between platforms
Setting up your system