Administrator Guide

Table Of Contents
Requirement Description
Replication Bandwidth
Controls
Replication Bandwidth Controls must be defined on the primary and secondary Storage
Centers.
Server
MPIO must be enabled on the server to prevent I/O interruption.
Live Volume Types
Live Volumes can be created using asynchronous replication or synchronous replication.
Storage Center version 7.3 and later provides support for ALUA optimization of Live Volumes.
Live Volume ALUA allows the Storage Center to report path priority to servers for Live Volumes. The servers can make use of
this path priority to prefer sending I/O to the better performing paths. In practice, I/O is directed towards the paths of the
Primary Live Volume.
In Unisphere Central, the Summary tab of a Live Volume reports whether a Live Volume is ALUA optimized. If Live Volumes exist
that are not ALUA optimized, Unisphere Central displays an alert and provides a link to a guided process to update Live Volumes
to ALUA optimized.
Live Volume Roles
There are two roles for Live Volumes: primary and secondary. These roles determine the direction of the replication, and they
can be swapped automatically or manually. Write performance is reduced for the secondary volume because the primary volume
must also acknowledge these writes.
Live Volume Role
Description
Primary
Hosts the primary volume, which is like the source volume for a conventional replication
Replicates the primary volume to the secondary volume
Processes all I/O from both the primary and secondary site
Secondary
Hosts the secondary volume
Accepts I/O for the Live Volume and routes it to the primary volume on the primary
Storage Center
Live Volume Roles Example
In the following examples, a server sends an IO request that modifies the primary volume. The changes to the primary volume
are replicated to the secondary Storage Center over Fibre Channel or iSCSI. When a server connected to the secondary Storage
Center sends an IO request to the secondary volume, the secondary Storage Center forwards the IO request to the primary
volume on the primary Storage Center.
Storage Center Replications and Live Volumes
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