Before starting a primary storage retirement
Typically, for a RAIN system, before starting a data migration, you submit a request to your authorized HCP service provider to add new nodes to the HCP system in order to maintain (or increase) the system storage capacity. However, if the nodes not selected for migration have sufficient free space to accommodate all the data to be migrated, adding new nodes before the data migration is not required.
For a SAIN system, before starting a data migration, your SAN storage administrator, working in conjunction with your authorized HCP service provider, needs to add logical volumes (LUNs) from new or existing storage systems to any nodes on which all the existing LUNs on all the existing arrays are being retired. Migrated data, however, can be written to any node, and does not necessarily have to be written to the same node from which the data is being migrated.
The HCP system cannot be upgraded while a data migration is in progress. Before the system can be upgraded, you need to either allow the migration to finish or cancel the migration. If you cancel the migration, you can configure a new migration of data off the same devices after the system is upgraded.