Veritas 5.0 Installation Guide, HP-UX 11i v3, First Edition, May 2008

• Volume Snapshot
Volume Snapshots are point in time images of VxVM volumes.
VxVM 5.0 does not support snapshots of RAID 5 volumes.
• Dirty Region Logging
Dirty Region logging (DRL) keeps track of the regions that have been changed because I/O
writes to a mirrored volume. The DRL uses this information to recover only those portions
of the volume that need to be recovered, thereby speeding up recovery after a system crash.
VxVM 5.0 on HP–UX 11i v3
For more information on features that VxVM 5.0 supports on HP-UX 11i v3, see the Veritas Volume
Manager 5.0 Release Notes, at http://docs.hp.com.
Architecture of VxVM
VxVM operates as a subsystem between the HP-UX operating system and other data management
systems, such as file systems and database management systems. VxVM is layered on top of the
operating system and is dependent on it for the following:
• Physical access to disks
• Device handles
• VM disks
• Multipathing
VxVM Daemons
VxVM relies on the following daemons for its operation:
• vxconfigd – The VxVM configuration daemon maintains disk and disk group configuration
information, communicates configuration changes to the kernel, and modifies the
configuration information stored on the disks.
• vxiod – The VxVM I/O daemon provides extended I/O operations without blocking the
calling processes.
• vxrelocd – The hot-relocation daemon monitors VxVM for events that affect redundancy,
and performs hot-relocation to restore redundancy.
VxVM Objects
VxVM supports the following types of objects:
• Physical Objects
Physical disks or other hardware with block and raw operating system device interfaces
that are used to store data.
• Virtual Objects
The virtual objects in VxVM include the following:
— Disk Group
A group of disks that share a common configuration. A configuration consists of a set
of records describing objects (including disks, volumes, plexes, and subdisks) that are
associated with one particular disk group. Each disk group has an administrator-assigned
name, which can be used by the administrator to reference that disk group. Each disk
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