Traditional data migration methods can be complex and disruptive, often
requiring extensive rewiring and reconfiguration of the SAN infrastructure.
Configuration changes to servers and storage subsystems require coordination
among different IT groups and storage vendor service representatives. Server
downtime requires advanced scheduling with potentially long lead times.
Cisco MDS DMM is an intelligent software application that runs on the
Cisco MDS 9000 18/4-Port Multiservice Module (MSM-18/4) or the MDS 9222i switch
or the MDS 9250i switch. With Cisco MDS DMM, no rewiring or reconfiguration is
required for the server, the existing storage, or the SAN fabric. The MSM-18/4
module, MDS 9222i switch or MDS 9250i switch can be located anywhere in the
fabric, as Cisco MDS DMM operates across the SAN. Data migrations are enabled
and disabled by software control from the Cisco Fabric Manager.
Cisco MDS DMM provides a graphical user interface (GUI) (integrated
into Fabric Manager) for configuring and executing data migrations. There is
also a command-line interface (CLI), which is suitable for creating scripts.
Cisco MDS DMM can be used in SANs that have only Cisco MDS 9000
switches as well as those containing a heterogeneous mixture of Cisco and other
Application downtime is a critical factor in data migration, as
prolonged periods of downtime are difficult to schedule. Cisco MDS DMM
minimizes application downtime. Existing data is available to the applications
while the migration is performed. Cisco MDS DMM uses hardware and software
resources on the MSM-18/4 module, MDS 9222i switch or the MDS 9250i switch to
move data to the new storage. This approach ensures that data migration adds no
processing overhead to the servers.
Cisco MDS DMM supports online migration, allowing applications to continue to access the existing storage devices. During data migration, all traffic between the server and storage flows through the MSM-18/4 module, MDS 9222i switch or the MDS 9250i switch, (Figure 1 (right side)). The MSM-18/4 module, MDS 9222i switch or the MDS 9250i switch coordinates all server access to the storage and performs the data migration. The migration activity is transparent to the server, which continues to have full access to the data Figure 1 (left side) shows the server’s view of the network during data migration. The server is unaware of the MSM-18/4 module, MDS 9222i switch or the MDS 9250i switch, the new storage, and the migration activity.
Figure 1. Data Migration Using Cisco MDS DMM
Cisco MDS DMM performs data migration without any additional layer of
virtualization. Cisco MDS DMM requires only the MSM-18/4 module, MDS 9222i
switch or the MDS 9250i switch configuration to enable the feature and SAN
configuration to access the new storage array. Cisco MDS DMM can be enabled
(when data needs to be migrated) and disabled (after the migration is
completed) without any major SAN or host reconfiguration.