Veritas Volume Manager 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

Adding Logs and Maps to Volumes
234 VERITAS Volume Manager Administrator’s Guide
For example, to dissociate and remove a mirror named vol01-02 from the disk group,
mydg, use the following command:
# vxplex -g mydg -o rm dis vol01-02
This command removes the mirror vol01-02 and all associated subdisks. This is
equivalent to entering the following separate commands:
# vxplex -g mydg dis vol01-02
# vxedit -g mydg -r rm vol01-02
Adding Logs and Maps to Volumes
In VERITAS Volume Manager, several types of volume logs and maps are supported:
◆ 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 volumes 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 Volum e
Layout” on page 51, and “Adding a Version 0 DCO and DCO Volume” on
page 307 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
“Preparing a Volume for DRL and Instant Snapshots” on page 235 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 enabling DRL on a volume:
◆ “Adding Traditional DRL Logging to a Mirrored Volume” on page 242 describes
how to add DRL log plexes to a volume.
◆ “Preparing a Volume for DRL and Instant Snapshots” on page 235 describes how
to configure DRL for a volume using 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.