3–Data Migration ObjectsOnline Remote MigrationISR654608-00 C 3-13 Schedule and start remote migration jobs at off peak hours, so that a smallnumber of dirty regions are generated, and most of the WAN bandwidth isavailable to perform the initial data copy. Follow the guidelines for DML size. Selecting the Yes and TP validationoption can result in a long migration time and may require more bandwidthbetween two sites. To ensure faster migration, migrate storage for a few servers at a time. Schedule the start of online remote migration during off peak hours toensure that the change rate is small during the initial copy period.Method 2: Initial Copy at Local Site and Copy Changes onRemote SiteScenario: In this method, first deploy either the destination storage or “swing”storage at a local location. After the initial copy is completed, ship the storage tothe remote location. At the remote location, make available the destinationstorage (or swing storage) to the local SAN either by using an FCIP link (whendestination storage for Fibre Channel), or by logging into the destination iSCSIstorage. These steps cause the changes to be replicated over distance. If using aswing storage, perform a separate data migration from the swing storage to a realdestination storage.The dedicated IP bandwidth between the two locations should be approximatelytwo times the change rate of the data under migration. This method is useful whenmigrating a large amount of data in a short time.Advantages: This method does not require a large IP bandwidth between twosites.Disadvantages: Because the initial copy is made locally before storage isshipped to the remote location, all applications and servers associated with thedestination storage array must be migrated at the same time.To avoid migrating all servers associated with the new array, use swing storage.Swing storage requires two copies: the initial copy from source to swing storage atthe local site, and the changes copied to swing storage at a remote site andcopied from the swing storage to the final destination storage.Best Practices: Ensure that the dedicated IP bandwidth between the two sites is availablefor data migration throughout the migration project. Migrate simultaneously all applications and servers associated with thedestination storage. Schedule the start of online remote migration at off peak hours, such that thechange rate is small during the initial copy period.
