VERITAS Storage Foundation 4.1 Oracle Administrator's Guide

VERITAS Volume Manager Prerelease 8 September 2005, 8:54am
24 VERITAS Storage Foundation for Oracle Administrator’s Guide
VERITAS Volume Manager
Databases require their storage media to be robust and resilient to failure. It is vital to protect
against hardware and disk failures and to maximize performance using all the available hardware
resources. Using a volume manager provides this necessary resilience and eases the task of
management. A volume manager can help you manage hundreds of disk devices and makes
spanning, striping, and mirroring easy.
VERITAS Volume Manager (VxVM) builds virtual devices called volumes on top of physical
disks. Volumes are accessed by a file system, a database, or other applications in the same way
physical disk partitions would be accessed. Using volumes, VxVM provides the following
administrative benefits for databases:
◆ Spanning of multiple disks—eliminates media size limitations.
◆ Striping—increases throughput and bandwidth.
◆ Mirroring or RAID-5—increases data availability.
◆ Online relayout—allows online volume layout changes to improve database performance.
◆ Volume resynchronization—ensures that all mirrors contain exactly the same data and that the
data and parity in RAID-5 volumes agree.
◆ Dirty Region Logging (DRL)—speeds the recovery of mirrored volumes after a system crash.
◆ SmartSync Recovery Accelerator—increases the availability of mirrored volumes by only
resynchronizing changed data.
◆ Volume snapshots—allows backup of volumes based on disk mirroring. With this release,
VxVM introduces full-sized and space-optimized instant snapshots, the preferred way to
implement online and off-host point-in-time copy solutions.
◆ FastResync—separately licensed, optional feature that performs quick and efficient
resynchronization of stale mirrors. FastResync is included with the Enterprise Edition and is
also included as part of the VERITAS FlashSnap option with the Standard Edition.
◆ Disk group split and join—separately licensed, optional feature that supports general disk
group reorganization and allows you to move volume snapshots to another host for off-host
backup. Disk group split and join is included with the Enterprise Edition and is also included
as part of the VERITAS FlashSnap option with the Standard Edition.
◆ Hot-relocation—automatically restores data redundancy in mirrored and RAID-5 volumes
when a disk fails.
◆ Dynamic multipathing (DMP)—allows for transparent failover, load sharing, and hot plugging
of SCSI devices.
◆ Volume sets—allows several volumes to be represented by a single logical mount device.
◆ Dynamic LUN Expansion—allows you to resize a disk after it has been initialized while
preserving the existing data on the disk.