Moving Your File Server to the Cloud: Choosing Between NAS, SharePoint, and Azure Files

Moving a file server to the cloud means replacing the data that used to sit on a physical in-house file server or NAS (network-attached storage) with a cloud-based storage location that can be accessed over the internet. Within a Microsoft environment there are several options — SharePoint, OneDrive, and Azure Files — each with different strengths.

Most companies start considering cloud migration because of frustrations that build up through day-to-day operation.

- Storage capacity is running low, and it's unclear when to add or replace hardware
- The device is aging and at risk of failure, creating uncertainty around backups
- Accessing files from outside the office or from home requires a VPN connection, which is cumbersome
- Data is routinely carried out on USB drives, with little control over where it ends up

The main options can be summarized as follows. Costs vary significantly depending on configuration and usage, so treat these figures only as a starting point for discussion.

Cloud migration isn't always the right call. In the following situations, it can be more rational to keep and simply update the existing NAS rather than force a migration.

- A small number of users with almost no need for access from outside the office
- Unstable line speed or network conditions that make cloud-based access impractical
- Internal policy or the sensitivity of the data requires storage to stay contained within the internal network

The basic cloud migration guide and the AWS vs. Azure comparison, which compares the strengths of each platform, can help with this decision. For use cases closer to object storage — such as backups or files behind a website — see the comparison of S3, Azure Blob, and GCS.

File server migrations tend to run into trouble less because of the data itself and more because of folder structure and permission design. Following this order helps avoid confusion.

- 1. Take stock of the current folder structure, users, and access permissions (and clean up unneeded data at the same time)
- 2. Design the folder structure and permission groups for the new location — don't simply copy the old structure as-is
- 3. Migrate a single department or folder as a trial, and confirm that business applications can still reference the files correctly
- 4. If it goes well, expand gradually, running the old NAS or server in parallel for a period before winding it down

SharePoint and OneDrive often fit within the storage already included in an existing Microsoft 365 contract, sometimes with no additional charge. Azure Files, on the other hand, is billed based on storage volume, access frequency, and data transfer, and is commonly discussed in the range of roughly a few thousand to a few tens of thousands of yen per month for tens to a few hundred gigabytes of use — but this is only a rough guide. Actual pricing varies with usage patterns and exchange rates, so it's worth running the numbers with Microsoft's official pricing calculator and comparing multiple quotes before committing. For a NAS replacement, the upfront hardware cost is the main factor, but comparing the total cost over several years — including maintenance, electricity, and the next replacement cycle — makes for a fairer comparison.

Moving a file server to the cloud isn't a single choice but a set of options — SharePoint/OneDrive, Azure Files, and simply replacing the NAS — that should be selected based on fit rather than which is objectively "best." Start by taking stock of current pain points and actual usage, run a small-scale trial migration, and then roll out more broadly. That sequence keeps both cost and operational risk under control.