Veritas Volume Manager 5.0 Migration Guide, HP-UX 11i v3, First Edition, May 2008

Glossary
block
A unit of space for data on a disk, typically having a size of 1024-bytes.
Dirty Region Logging
Dirty Region Logging (DRL) is an optional property of a volume, used to provide a speedy
recovery of mirrored volumes after a system failure. DRL keeps track of the regions that
have changed due to I/O writes to a mirrored volume.
file system
The organization of files on storage devices. The term file system can refer either to the
entire file system or to a subsection of that file system, contained within a disk section or a
logical volume that can be mounted or unmounted from that tree.
logical volume
A logical structure that is a map of storage areas on physical volumes. A logical volume can
be conceptualized as a storage device of flexible size. The data in a logical volume can be
mapped to one or more physical volumes. A virtual disk device that represents a
contiguous virtual disk space that maps to single or multiple areas on a single or multiple
physical volumes.
LVM
The Logical Volume Manager (LVM) is a subsystem for managing disk space. LVM is an HP-
UX product, similar to VxVM.
LIF
The Logical Interchange Format (LIF) is a HP mass-storage format that can be used for
interchange of files among various HP computer systems. Each boot disk has a LIF
directory that contains boot programs.
logical Extent
A set of logical blocks that maps to one physical extent and is a basic unit of access in a
logical volume.
LVMREC
The LVM record, which is an identifier that is set on each disk when it is initialized the first
time by LVM. There are two copies of the LVMREC; one is at sector 8, while the other is at
sector 72.
mirror disk/UX
HP-UX software product that allows disk mirroring as part of LVM functionality. Mirror
Disk/UX allows up 2 mirror copies in a volume.
Mirror Write Cache (MWC)