Common Terms

Active Partition

The 'active partition' on a disk drive has a special meaning according to the IBM PC partitioning scheme. It indicates the partition from which standard PC BIOS MBR boot code will attempt to boot. (Note that the OS/2 MBR boot code uses the 'Startable' flag for this purpose.) The active partition flag applies only to primary partitions, and is indicated by the value 0x80 as the first byte of the partition's entry in the partition table.

Bootable

The term 'Bootable' within the context of LVM specifically means a partition or volume which has an entry on the Boot Manager menu. Partitions or volumes may only be designated as Bootable when Boot Manager is present and active on the system.

Compatibility Volume

A compatibility volume is a volume which is compatible with non-LVM-aware operating systems. It consists of a single partition (primary or logical) which is seen simply as a standard partition by other operating systems.

Hidden Volume

A 'hidden' volume is a volume which does not currently have a drive letter assigned to it, and which is therefore not accessible by the user.

Installable

'Installable' is a special flag which is used only by the OS/2 install program, which uses it to identify the volume onto which OS/2 will be installed. This flag should not be set or used at any time other than during operating system installation.

Logical Volume

A logical volume (also simply 'volume') consists of one or more partitions which are seen by the operating system as a single logical allocation unit, capable of being assigned a drive letter and formatted with a filesystem. Volumes are classified as either Compatibility or LVM volumes.

LVM Volume

An LVM volume is a type of volume which is capable of containing multiple partitions, and of being formatted using the original implementation of the IBM Journalled File System. All partitions belonging to an LVM volume have a type indicator of 0x35, and are not generally usable by non-LVM-aware operating systems.

Partition

LVM uses the term 'partition' to refer to any block of disk space which corresponds either to a standard partition (according to the IBM PC partitioning scheme) or to a contiguous region of free space.

Startable

A partition or volume which is 'Startable' is identified as the startup (boot) partition in the master boot record, to be booted directly when the system starts. Only primary partitions (or volumes consisting of one primary partition) may be set Startable, and only one partition or volume may be Startable at any one time.