When working with containers to store data, the database manager supports direct disk access (raw I/O).
This type of support allows you to attach a direct disk access (raw) device to any DB2® database system.
You must know the device or file names of the containers you are going to reference when creating your table spaces. You must know the amount of space associated with each device or file name that is to be allocated to the table space. You will need the correct permissions to read and write to the container.
For Windows, there is a new method for specifying DMS raw table space containers. Volumes (that is, basic disk database partitions or dynamic volumes) are assigned a globally unique identifier (GUID) when they are created. The GUID can be used as a device identifier when specifying the containers in a table space definition. The GUIDs are unique across systems which means that in a multi-partition database, GUIDs are different for each database partition even if the disk partition definitions are the same.
A tool called db2listvolumes.exe is available (only on Windows operating systems) to make it easy to display the GUIDs for all the disk volumes defined on a Windows system. This tool creates two files in the current directory where the tool is run. One file, called volumes.xml, contains information about each disk volume encoded in XML for easy viewing on any XML-enabled browser. The second file, called tablespace.ddl, contains the required syntax for specifying table space containers. This file must be updated to specify the remaining information needed for a table space definition. The db2listvolumes command does not require any command line arguments.
After you create a logical volume, you can change its name and characteristics with the chlv command, and you can increase the number of logical partitions allocated to it with the extendlv command. The default maximum size for a logical volume at creation is 512 logical partitions, unless specified to be larger. The chlv command is used to override this limitation.
Within AIX®, the set of operating system commands, library subroutines, and other tools that allow you to establish and control logical volume storage is called the Logical Volume Manager (LVM). The LVM controls disk resources by mapping data between a simpler and flexible logical view of storage space and the actual physical disks.
For more information about the mklv and other logical volume commands, and the LVM, refer to AIX 5L™ Version 5.2 System Management Concepts: Operating System and Devices.