Here’s the practical way to think about it:

1) File storage

What it is: Shared storage accessed through a filesystem, usually over NFS/SMB.
Examples: Amazon EFS, Azure Files, Google Filestore.

Pros

• Easy lift-and-shift for legacy apps that expect a mounted drive.
• Shared namespace: multiple servers can read/write the same files.
• Familiar semantics: directories, filenames, permissions, file locking.

Cons

• Often more expensive per GB than object storage.
• Performance depends on service and access pattern; can be great for general sharing but not always ideal for very high IOPS workloads.
• Still limited by filesystem behavior and locking semantics.
• Usually not the best fit for massive unstructured data or internet-scale storage.

Best for

• Home directories
• App shared content
• Content management
• Legacy apps that require POSIX-like filesystem access

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2) Block storage

What it is: Raw storage volumes attached to one machine, which you format and mount as a disk.
Examples: Amazon EBS, Azure Managed Disks, Google Persistent Disk.

Pros

• Low-latency, high-performance storage for a single instance.
• Good for databases and apps that need direct disk access.
• You control the filesystem and layout.

Cons

• Typically attached to one host at a time (or limited multi-attach options depending on cloud/service).
• Not shared like a file server.
• You must manage filesystem, partitioning, snapshots, and sometimes volume resizing.
• Not ideal for many-app or many-server access to the same data.

Best for

• Databases
• VM boot volumes
• Stateful apps needing high performance
• Applications that need a local disk abstraction

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3) Object storage

What it is: Storage for data as objects accessed via an API (HTTP/REST), not mounted as a filesystem by default.
Examples: Amazon S3, Azure Blob Storage, Google Cloud Storage.

Pros

• Massively scalable and highly durable.
• Usually the lowest cost for storing large amounts of data.
• Great for backups, archives, logs, media, data lakes.
• Easy to access from apps over the network.
• Built-in features like versioning, lifecycle policies, replication, immutability.

Cons

• Not a filesystem: no true directories, POSIX locking, or rename semantics like a file server.
• Applications must use object APIs.
• Higher latency than local/block storage for many workloads.
• Random small reads/writes and frequent overwrites are usually a poor fit.

Best for

• Backups and archives
• Static content and media
• Logs
• Analytics/data lake workloads
• Cloud-native apps that can use APIs directly

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Quick comparison

Feature	File	Block	Object
Access style	Mount as filesystem	Raw disk attached to server	API/HTTP calls
Shared among servers	Yes	Usually no	Yes
POSIX filesystem semantics	Yes	Yes, after formatting/mounting	No
Latency	Medium	Low	Higher
Scalability	Moderate	Per-volume limits	Very high
Cost efficiency	Medium	Medium/high	Best
Best use cases	Shared app files	Databases, OS disks	Backup, archive, unstructured data

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For replacing a legacy file server

If your application expects:

• SMB/NFS shares, use managed file storage.
• A disk attached to one server, use block storage.
• To be modernized to use API-based access, use object storage.

Common migration pattern

• If the app is legacy and expects shared folders: managed file storage is usually the closest replacement.
• If the app is database-like or needs fast local disk: block storage.
• If the data is mostly documents, images, logs, or backups and the app can change: object storage can be the most scalable and cost-effective choice.

If you want, I can also help you decide based on your specific workload, like:

• number of servers accessing the data
• read/write patterns
• file sizes
• performance requirements
• whether the app supports SMB/NFS/object APIs