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274 Administering volumes
Adding logs and maps to volumes
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 66 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
“Version 0 DCO volume layout” on page 69, and “Adding a version 0
DCO and DCO volume” on page 356 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 “Version 20 DCO volume
layout” on page 69, and “Preparing a volume for DRL and instant
snapshots” on page 275 for more information.
See “Enabling FastResync on a volume” on page 292 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” on page 60 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 281
describes how to add DRL log plexes to a volume.
■ “Preparing a volume for DRL and instant snapshots” on page 275
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 50 for details). These logs are
configured as plexes on disks other than those that are used for the columns
of the RAID-5 volume.
See “Adding a RAID-5 log” on page 283 for information on adding RAID-5
logs to a RAID-5 volume.