Glossary 523

maintained in the DCO volume. Otherwise, the DRL is allocated to an associated subdisk called a log subdisk.

disabled path

A path to a disk that is not available for I/O. A path can be disabled due to real hardware failures or if the user has used the vxdmpadm disable command on that controller.

disk

A collection of read/write data blocks that are indexed and can be accessed fairly quickly. Each disk has a universally unique identifier.

disk access name

An alternative term for a device name.disk access records

Configuration records used to specify the access path to particular disks. Each disk access record contains a name, a type, and possibly some type-specific information, which is used by VxVM in deciding how to access and manipulate the disk that is defined by the disk access record.

disk array

A collection of disks logically arranged into an object. Arrays tend to provide benefits such as redundancy or improved performance. Also see disk enclosure and JBOD.

disk array serial number

This is the serial number of the disk array. It is usually printed on the disk array cabinet or can be obtained by issuing a vendor- specific SCSI command to the disks on the disk array. This number is used by the DMP subsystem to uniquely identify a disk array.

disk controller

In the multipathing subsystem of VxVM, the controller (host bus adapter or HBA) or disk array connected to the host, which the operating system represents as the parent node of a disk.

disk enclosure

An intelligent disk array that usually has a backplane with a built-in Fibre Channel loop, and which permits hot-swapping of disks.

disk group

A collection of disks that share a common configuration. A disk group configuration is a set of records containing detailed information on existing VxVM objects (such as disk and volume attributes) and their relationships. Each disk group has an administrator-assigned name and an internally defined unique ID. The disk group names bootdg (an alias for the boot disk group), defaultdg (an alias for the default disk group) and nodg (represents no disk group) are reserved.

disk group IDA unique identifier used to identify a disk group.disk ID

A universally unique identifier that is given to each disk and can be used to identify the disk, even if it is moved.

disk media name