Yes, you can keep the FI's in FC switching mode and still have them login to the MDS Fabric during the migration process. However, you should be aware of the potential issues and limitations that may arise due to the different modes of operation.
Here's a high-level overview of the migration process:
1. Keep the FI's in FC switching mode and connect them to the MDS Fabric. MDS interfaces connecting to the FI should be configured in trunking E mode. Make sure to configure the required zoning on the MDS switches to allow communication between the hosts, old SAN storage, and Pure storage arrays.
2. Perform the data migration from the old direct-attached SAN storage to the new Pure arrays. You can use data migration tools like VMware Storage vMotion, Microsoft Storage Migration Service, or other third-party tools depending on your environment and requirements.
3. Once the data migration is complete and you have verified that everything is working as expected, you can then proceed to change the FI's mode to FC End Host mode. Please note that changing the mode will require a reboot of the FI's, so plan for a maintenance window accordingly. MDS interfaces connecting to the FIs should be updated to F-mode and the NPIV feature should be enabled.
4. After switching the FI's to FC End Host mode, update the zoning configuration on the MDS switches if necessary, and verify that everything is functioning correctly.
As an alternative, you can consider using a temporary FC switch to bridge the connection between the old direct-attached SAN storage and the new Pure arrays during the migration process. This would allow you to configure the FI's in FC End Host mode from the beginning, avoiding the need to change the mode later on. However, this option may require additional hardware and configuration efforts.
In summary, it is possible to keep the FI's in FC switching mode during the migration process and change to FC End Host mode afterward. Make sure to plan and test the migration process thoroughly to minimize the risk of downtime or data loss.