Dell SRDF Introduction

Normal flow

The steps in the migration process that are usually followed are:

1. Set up the migration environment – configure the infrastructure of the source and target array, in preparation for data migration.
2. On the source array, select a storage group to migrate.
3. If using Minimally Disruptive Migration (MDM) from PowerMaxOS 10 (6079)), shut down the application associated with the storage group.
4. Create the migration session optionally specifying whether to move the identity of the LUNs in the storage group to the target array – copy the content of the storage group to the target array using SRDF/Metro.

   During this time, the source and target arrays are both accessible to the application host.

5. When the data copy is complete:
   1. If the migration session did not move the identity of the LUNs, reconfigure the application to access the new LUNs on the target array.
   2. Commit the migration session – remove resources from the source array and those used in the migration itself.
6. If using NDM Updates, restart the application.
7. To migrate further storage groups, repeat steps 2 to 6.
8. After migrating all the required storage groups, remove the migration environment.

Alternate flow

There is an alternative process that pre-copies the data to the target array before making it available to the application host. The steps in this process are:

1. Set up the migration environment – configure the infrastructure of the source and target array, in preparation for data migration.
2. On the source array, select a storage group to migrate.
3. Use the precopy facility of NDM to copy the selected data to the target array.

   Optionally, specify whether to move the identity of the LUNs in the storage group to the target array.

   While the data copy takes place, the source array is available to the application host, but the target array is unavailable.

4. When the copying of the data is complete: Use the Ready Target facility in NDM to make the target array available to the application host also.
   1. If the migration session did not move the identity of the LUNs, reconfigure the application to access the new LUNs on the target array.
   2. If using MDM, restart the application.
   3. Commit the migration session: Remove resources from the source array and those resources used in the migration itself. The application now uses the target array only.
5. To migrate further storage groups, repeat steps 2 to 4.
6. After migrating all the required storage groups, remove the migration environment.

Other functions

Other NDM facilities that are available for exceptional circumstances are:

• Cancel – to cancel a migration that has not yet been committed.
• Sync – to stop or start the synchronization of writes to the target array back to source array. When stopped, the application runs on the target array only. Used for testing.
• Recover – to recover a migration process following an error.