# Restrictions and Limitations

#### Restrictions

- SFS supports the NFSv3 protocol only. The default export options are rw, no_root_squash, no_all_squash, and sync.
- To obtain better performance, you are advised to use the operating systems listed in Supported Operating Systems, which have passed the compatibility test.
- Currently, SFS does not support replication.
- Currently, SFS does not support cross-region access.
- SFS Capacity-Oriented does not apply to file storage scenarios requiring low latency and high IOPS, such as database services, website building, and code storage.

#### SFS Capacity-Oriented

- SFS Capacity-Oriented can be accessed only on the intranet and used only on the cloud.

- Currently, NFSv3 protocol is supported (NFSv4 is not supported).
- A maximum of 10,000 compute nodes can be mounted to and access a single file system at the same time.
- The maximum capacity of a single file system is 2 PB, and that of a single file is 240 TB.
- Multiple VPCs are supported. You can add a maximum of 20 VPCs for each file system. A maximum of 400 ACL rules for added VPCs can be created.

#### SFS Turbo

- Only the NFSv3 protocol is supported (NFSv4 is not supported).
- A maximum of 500 compute nodes can be mounted to and access a single file system at the same time.
- The maximum capacity of a single file system is 32 TB, and the maximum capacity of a single file is 16 TB.
- Maximum number of files supported by a single file system = Capacity/16 KB. For example, the maximum number of files supported by a 500 GB file system is 32,768,000 (500 GB/16 KB = 500 x 1024 x 1024/16).
- By default, a single directory contains a maximum of 2 million files.
- The maximum full path is 1024 bytes, and the maximum file name length is 255 bytes.
- The maximum soft link length is 1024 bytes.
- The maximum number of hard links is 255.
- The maximum directory depth is 100 layers.

Parent topic: Introduction