Veritas FlashSnap Point-In-Time Copy Solutions 5.0.1 Administrators Guide, HP-UX 11i v3, First Edition, November 2009

■ Veritas Storage Foundation Installation Guide

■ Veritas File System Administrator’s Guide

■ Veritas Volume Manager Administrator’s Guide

■ Symantec NetBackup DataCenter Installation Guide

■ Symantec NetBackup DataCenter System Administrator’s Guide

■ Symantec NetBackup ServerFree Agent System Administrator’s Guide

■ Symantec NetBackup for Oracle ServerFree Agent System Administrator’s Guide

■ Symantec NetBackup BusinesServer Getting Started Guide

■ Symantec NetBackup BusinesServer System Administrator’s Guide

Persistent FastResync of volume snapshots

Veritas Volume Manager allows you to take multiple snapshots of your data at

the level of a volume. A snapshot volume contains a stable copy of a volume’s data

at a given moment in time that you can use for online backup or decision support.

If persistent FastResync is enabled on a volume, VxVM uses a FastResync map to

keep track of which blocks are updated in the volume and in the snapshot. If the

data in one mirror is not updated for some reason, it becomes out-of-date, or stale,

with respect to the other mirrors in the volume. The presence of the FastResync

map means that only those updates that the mirror has missed need be reapplied

to resynchronize it with the volume. A full, and therefore much slower,

resynchronization of the mirror from the volume is unnecessary.

When snapshot volumes are reattached to their original volumes, persistent

FastResync allows the snapshot data to be quickly refreshed and re-used. Persistent

FastResync uses disk storage to ensure that FastResync maps survive both system

and cluster crashes. If persistent FastResync is enabled on a volume in a private

disk group, incremental resynchronization can take place even if the host is

rebooted.

Persistent FastResync can track the association between volumes and their

snapshot volumes after they are moved into different disk groups. After the disk

groups are rejoined, persistent FastResync allows the snapshot plexes to be quickly

resynchronized.

See the Veritas Volume Manager Administrator’s Guide.

Instant volume snapshots

The traditional type of volume snapshot that was provided in VxVM is of the

third-mirror type. This name comes from its original implementation by adding

Point-in-time copy solutions

Veritas software used in point-in-time copy scenarios