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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 25.
Note
Disks with format cdsdisk can only be added to disk groups with version 110 or later.
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 configuration database. The default private region size is 32MB, which is large enough to record the details of several thousand VxVM objects in a disk group.
The public region covers the remainder of the disk, and is used for the allocation of storage space to subdisks.
The private and public regions are aligned and sized in multiples of 8K to permit the operation of CDS. The alignment of VxVM objects within the public region is controlled by the disk group alignment attribute. The value of the disk group alignment attribute must also be 8k to permit the operation of CDS.
Note
With other (non-CDS) VxVM disk formats, the private and public regions are aligned to the platform-specific OS block size.
The disk access (DA) disk type auto supports multiple disk formats, including cdsdisk, which is supported across all platforms. It is associated with the DA records created by the VxVM auto-configuration mode. Disk type auto automatically determines which format is on the disk.
The platform block resides on disk sector 0, and contains data specific to the operating system for the platforms. It is necessary for proper interaction with each of those platforms. The platform block allows a disk to perform as if it was initialized by each of the specific platforms.
The AIX coexistence label resides on the disk, and identifies the disk to the AIX logical volume manager (LVM) as being controlled by VxVM.
The HP-UX coexistence label resides on the disk, and identifies the disk to the HP logical volume manager (LVM) as being controlled by VxVM.
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.