Dell EMC Metro node 7.0.1 Product Guide

In typical IT environments, migrations to new storage arrays (technology refreshes) require that the data that is being used by hosts be copied to a new volume on the new array. The host must then be reconfigured to access the new storage. This process requires downtime for the host.

Metro node makes it easier to replace heterogeneous storage arrays on the back-end. Migrations between heterogeneous arrays can be complicated and may require additional software or functionality. Integrating heterogeneous arrays in a single environment is difficult and requires a staff with a diverse skill set.

When metro node is inserted between the front-end and back-end redundant fabrics, metro node appears as the target to hosts and as the initiator to storage.

The data resides on virtual volumes in metro node and it can be copied nondisruptively from one array to another without any downtime. There is no need to reconfigure the host; the physical data relocation is performed by metro node transparently and the virtual volumes retain the same identities and the same access points to the host.

In the following figure, the virtual disk is made up of the disks of Array A and Array B. The site administrator has determined that Array A has become obsolete and should be replaced with a new array. Array C is the new storage array. Using Mobility Central, the administrator:

• Adds Array C into the metro node cluster.
• Assigns a target extent from the new array to each extent from the old array.
• Instructs metro node to perform the migration.

Metro node copies data from Array A to Array C while the host continues its access to the virtual volume without disruption.

After the copy of Array A to Array C is complete, Array A can be decommissioned:

Because the virtual machine is addressing its data to the abstracted virtual volume, its data continues to flow to the virtual volume without any need to change the address of the data store.

Although this example uses virtual machines, the same is true for traditional hosts. Using metro node, the administrator can move data used by an application to a different storage array without the application or server being aware of the change.

This allows you to change the back-end storage arrays transparently, without interrupting I/O.