Veritas Volume Manager 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)
Chapter 7, Creating Volumes
Types of Volume Layouts
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A striped-mirror volume is created by configuring several mirrored volumes as the
columns of a striped volume. This layout offers the same benefits as a non-layered
mirrored-stripe volume. In addition it provides faster recovery as the failure of single
disk does not force an entire striped plex offline. For more information, see “Mirroring
Plus Striping (Striped-Mirror, RAID-1+0 or RAID-10)” on page 26.
A concatenated-mirror volume is created by concatenating several mirrored volumes.
This provides faster recovery as the failure of a single disk does not force the entire
mirror offline.
Supported Volume Logs and Maps
VERITAS Volume Manager supports the use of several types of logs and maps with
volumes:
◆ FastResync Maps are used to perform quick and efficient resynchronization of mirrors
(see “FastResync” on page 49 for details). These maps are supported either in memory
(Non-Persistent FastResync), or on disk as part of a DCO volume (Persistent
FastResync). Two types of DCO volume are supported:
◆ Version 0 DCO volumes only support Persistent FastResync for the traditional
third-mirror break-off type of volume snapshot. See “Versi on 0 DCO Volume
Layout” on page 51, and “Creat ing a Volume w ith a Ver sio n 0 DCO Vol ume” on
page 210 for more information.
◆ Version 20 DCO volumes, introduced in VxVM 4.0, support DRL logging (see
below) and Persistent FastResync for full-sized and space-optimized instant
volume snapshots. See “Vers ion 20 D C O Volume Lay out” on page 51, and
“Creating a Volume with a Version 20 DCO Volume” on page 212 for more
information.
See “Enabling FastResync on a Volume” on page 252 for information on how to enable
Persistent or Non-Persistent FastResync on a volume.
◆ Dirty region logs allow the fast recovery of mirrored volumes after a system crash (see
“Dirty Region Logging (DRL)” on page 42 for details). These logs are supported either
as DRL log plexes, or as part of a version 20 DCO volume. Refer to the following
sections for information on creating a volume on which DRL is enabled:
◆ “Creating a Volume with Dirty Region Logging Enabled” on page 213 for creating
a volume with DRL log plexes.
◆ “Creating a Volume with a Version 20 DCO Volume” on page 212 for creating a
volume with DRL configured within a version 20 DCO volume.
◆ RAID-5 logs are used to prevent corruption of data during recovery of RAID-5
volumes (see “RAID-5 Logging” on page 33 for details). These logs are configured as
plexes on disks other than those that are used for the columns of the RAID-5 volume.