DataSync with NFS

Question

There are 2 On-prem Linux VM that is planned to be migrated to AWS. This Linux VM has both Block devices and 2 NFS exports(from FS of a Storage array) mounted on it. 
Block devices can be migrated using MGN. What should be the approach for array based NFS exports

The same on-prem File System has multiple NFS exports in addition to above 2 exports and those are mounted on multiple other on-prem hosts that is not decided to be migrated yet or to be migrated in multiple other waves

How to approach in this scenario

1. Whether to keep the File system in on-prem itself and create a Storage File Gateway to allow NFS access for the migrated cloud servers and also for the On-prem servers to access NFS exports (to achieve shared access)

2. Once all the on-prem servers are migrated to AWS then is it good to have Datasync migrate all on-prem FS to AWS and then take a downtime window to change the NFS server Mount IP's on all migrated servers

Answer

> keep the File system in on-prem itself and create a Storage File Gateway to allow NFS access for the migrated cloud servers

I don't think that will work for the use case you have in mind.

Ultimately, your end state is almost certain to be Linux VMs -> EC2, and storage migrated NFS -> EFS, and I can't see how you can achieve that end state while using Storage Gateway as a kind of "intermediate state".

Storage Gateway allows on-prem VMs to consume storage in AWS, but not in the other direction. At back end it's either S3, EBS, or FSx - look at the main [**How it works**](https://d1.awsstatic.com/pdp-how-it-works-assets/product-page-diagram_AWS-Storage-Gateway_HIW@2x.6df96d96cdbaa61ed3ce935262431aabcfb9e52d.png) diagram at https://aws.amazon.com/storagegateway/

Depending on the latency (and a factor could be how far you are from an AWS region) and if you have a resilient DX connection, you could use DataSync to migrate on-prem NFS to EFS in the cloud, and then the on-prem VMs and the EC2 instances could all consume the EFS filesystems. Then progressively migrate the VMs to EC2 until they have all come across.

Be aware that you can't do continual updates using DataSync, the shortest interval for running DataSync jobs is one hour https://docs.aws.amazon.com/datasync/latest/userguide/task-scheduling.html

DataSync with NFS

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