Veritas Storage Foundation Portable Data Containers: Cross-Platform Data Sharing 5.0.1 Administrators Guide, HP-UX 11i v3, First Edition, November 2009

Device level.Operating system

CDS is a license-enabled feature that is supported at the disk group level by VxVM

and at the file system level by VxFS.

CDS utilizes a new disk type (auto:cdsdisk). To effect data sharing, VxVM supports

a new disk group attribute (cds) and also supports different OS block sizes.

Note: CDS allows data volumes and their contents to be easily migrated between

heterogeneous systems. It does not enable concurrent access from different types

of platform unless such access is supported at all levels that are required.

Shared data across platforms

While volumes can be exported across platforms, the data on the volumes can be

shared only if data sharing is supported at the application level. That is, to make

data sharing across platforms possible, it must be supported throughout the entire

software stack.

For example, if a VxFS file system on a VxVM volume contains files comprising

a database, then the following functionality applies:

■ Disks can be recognized (as cds disks) across platforms.

■ Disk groups can be imported across platforms.

■ The file system can be mounted on different platforms.

However, it is very likely that, because of the inherent characteristics of databases,

you may not be able to start up and use the database on a platform different from

the one on which it was created. (A notable exception is Oracle 10g's Cross-Platform

Transportable Tablespace feature.)

An example is where an executable file, compiled on one platform, can be accessed

across platforms (using CDS), but may not be executable on a different platform.

Note: You do not need a file system in the stack if the operating system provides

access to raw disks and volumes, and the application can utilize them. Databases

and other applications can have their data components built on top of raw volumes

without having a file system to store their data files.

Disk drive sector size

Sector size is an attribute of a disk drive (or SCSI LUN for an array-type device),

which is set when the drive is formatted. Sectors are the smallest addressable unit

Overview of CDS

General concepts