VERITAS Volume Manager 4.1 Administrator's Guide

Understanding VERITAS Volume Manager
VxVM and the Operating System
Chapter 12
VxVM and the Operating System
VxVM operates as a subsystem between your operating system and your
data management systems, such as file systems and database
management systems. VxVM is tightly coupled with the operating
system. Before a disk can be brought under VxVM control, the disk must
be accessible through the operating system device interface. VxVM is
layered on top of the operating system interface services, and is
dependent upon how the operating system accesses physical disks.
VxVM is dependent upon the operating system for the following
functionality:
• operating system (disk) devices
• device handles
• VxVM dynamic multipathing (DMP) metadevice
This guide introduces you to the VxVM commands which are used to
carry out the tasks associated with VxVM objects. These commands are
described on the relevant manual pages and in the chapters of this guide
when VxVM tasks are described.
VxVM relies on the following constantly running daemons for its
operation:
• vxconfigd—The VxVM configuration daemon maintains disk and
group configurations and communicates configuration changes to the
kernel, and modifies configuration information stored on disks.
• vxiod—The VxVM I/O daemon provides extended I/O operations
without blocking calling processes. Several daemons are usually
started at boot time, and continue to run at all times.
• vxrelocd—The hot-relocation daemon monitors VxVM for events
that affect redundancy, and performs hot-relocation to restore
redundancy.