Veritas™ File System 5.0.1 Administrator's Guide

About multi-volume support
VxFS provides support for multi-volume file systems when used in conjunction
with the Veritas Volume Manager. Using multi-volume support (MVS), a single
file system can be created over multiple volumes, each volume having its own
properties. For example, it is possible to place metadata on mirrored storage while
placing file data on better-performing volume types such as RAID-1+0 (striped
and mirrored).
The MVS feature also allows file systems to reside on different classes of devices,
so that a file system can be supported from both inexpensive disks and from
expensive arrays. Using the MVS administrative interface, you can control which
data goes on which volume types.
Note: MVS is available only on file systems using disk layout Version 6 or later.
See “About disk layouts” on page 255.
About volume types
VxFS utilizes two types of volumes, one of which contains only data, referred to
as dataonly, and the other of which can contain metadata or data, referred to as
metadataok.
Data refers to direct extents, which contain user data, of regular files and named
data streams in a file system.
Metadata refers to all extents that ar enot regular file or name data stream extents.
This includes certain files that appear to be regular files, but are not, such as the
File Change Log file.
A volume availability flag is set to specify if a volume is dataonly or metadataok.
The volume availability flag can be set, cleared, and listed with the fsvoladm
command.
See the fsvoladm(1M) manual page.
Features implemented using multi-volume support
The following features can be implemented using multi-volume support:
■ Controlling where files are stored can be selected at multiple levels so that
specific files or file hierarchies can be assigned to different volumes. This
functionality is available in the Veritas File System Dynamic Storage Tiering
(DST) feature.
Multi-volume file systems
About multi-volume support
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