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

CDS disk access and format
For a disk to be accessible by multiple platforms, the disk must be consistently
recognized by the platforms, and all platforms must be capable of performing I/O
on the disk. CDS disks contain specific content at specific locations to identify or
control access to the disk on different platforms. The same content and location
are used on all CDS disks, independent of the platform on which the disks are
initialized.
In order for a disk to be initialized as, or converted to a CDS disk, it must satisfy
the following requirements:
■ Must be a SCSI disk
■ Must be the entire physical disk (LUN)
■ Only one volume manager (such as VxVM) can manage a physical disk (LUN)
■ There can be no disk partition (slice) which is defined, but which is not
configured on the disk
■ Cannot contain a volume whose use-type is either root or swap (for example,
it cannot be a boot disk)
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 467.
CDS disk types
The CDS disk format, cdsdisk, is recognized by all VxVM platforms (including
Windows). The cdsdisk disk format is the default for all newly-created VM disks
unless overridden in a defaults file. The vxcdsconvert utility is provided to convert
other disk formats and types to CDS.
See “Defaults files” on page 471.
Note: Disks with format cdsdisk can only be added to disk groups with version
110 or later.
Private and public regions
A VM disk usually has a private and a public region.
The private region is a small area on the disk where VxVM configuration
information is stored, such as a disk header label, configuration records for VxVM
objects (such as volumes, plexes and subdisks), and an intent log for the
Migrating data between platforms
CDS disk format and disk groups
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