Installation manual

Shadowing a Volume
Before You Begin
CLI Storage-Management Guide 15-3
Before You Begin
Shadow volumes are commonly deployed on separate switches from the source
volume, as pictured above. Before you configure the shadow volume on a target
switch, you must first
1. make a RON tunnel from the source switch to the target switch (see Chapter 5,
Joining a RON, in the CLI Network-Management Guide), and
2. add a namespace and source volume at the source switch (see Chapter 7,
Configuring a Namespace and Chapter 9, Adding a Managed Volume).
3. add a namespace at the target switch.
You then perform the procedures in this chapter: you start by adding a shadow volume
to the target switch, then you configure a shadow-copy rule at the source switch.
Adding a Shadow Volume (Target Switch)
The first step in shadowing a volume is configuring a second managed volume as a
shadow. A shadow volume is different from a standard managed volume in that it can
only contain replicas of source-volume files, and only the policy engine can write to
it.
A shadow volume starts as managed volume (see “Adding a Volume” on page 7-21).
To create the shadow volume on a different switch from the source volume, log into
the target switch’s CLI or GUI and add a new volume. Once the volume is created and
you are in gbl-ns-vol mode, use the
shadow command to change the managed volume
into a shadow volume:
shadow
The CLI presents a prompt to warn that all extraneous files will be removed from the
shadow volume’s shares; you must answer yes for the volume to become a shadow
volume. During the first shadow-copy operation, the rule replaces any files that are
different from their source-file counterparts, and then it deletes all files that are not
among the source files.