Notes and Constraints

SFS Capacity-Oriented

**Table 1** SFS Capacity-Oriented restrictions
Item	Description
Access method	SFS Capacity-Oriented file systems can only be accessed over the intranet and used on the cloud.
Supported protocols	Only NFSv3 is supported (NFSv4 is not supported), and CIFS is supported (SMB 2.0, 2.1, and 3.0 are supported, but SMB 1.0 is not supported). Export options with NFSv3 include rw, no_root_squash, no_all_squash, and sync. Export options with CIFS include rw and sync. Encrypted CIFS file systems do not support copychunk. CIFS file systems cannot be mounted to Linux servers. A file system can use either the NFS or CIFS protocol. It cannot use both protocols. SMB file systems provide permission control only on the file systems, but not on files or directories.
Max. number of clients per file system	10,000
Max. capacity per file system	4 PB
Max. size of a single file	240 TB
Multi-VPC access	Supported. You can add a maximum of 20 VPCs for one file system and create a maximum of 400 ACL rules for all added VPCs.
Max. enterprise projects supported	20. If there are more than 20 enterprise projects, SFS Capacity-Oriented file systems may fail to be created. SFS Turbo is recommended.
Replication	Not supported
Cross-region mounting	Not supported
Cross-account mounting	Not supported

SFS Capacity-Oriented file systems are now sold out. You can use General Purpose File System or SFS Turbo.

General Purpose File System

**Table 2** General purpose file system restrictions
Item	Description
Access method	Can only be accessed over the intranet.
Supported protocols	Only NFSv3 is supported (NFSv4 is not supported).
Max. number of clients per file system	10,000
File system encryption	Not supported
Number of files or subdirectories in a file system	Unlimited
Max. number of files or subdirectories in a single directory	30 million
File system name	Must be globally unique. It cannot be the same as the name of any existing general purpose file system, including one created by the current user or any other user. And it cannot be changed after the file system is created.
File system deletion	If a general purpose file system is deleted, you can only create a general purpose file system with the same name as the deleted one 30 minutes after that file system has been deleted.
Client OS	Cannot be mounted to 32-bit Linux servers. Cannot be mounted to Windows servers.
Changing root directory permissions	Not supported
Restrictions in the CCE and CCI scenarios	When General Purpose File System is used as the storage backend of CCE or CCI, you need to empty the in-use file systems before you can delete any PVCs or PVs. If you directly delete the PVCs or PVs, the file systems may fail to be deleted. Check whether the file systems are deleted on the General Purpose File System console. Deleting PVCs or PVs takes some time. The billing ends until the corresponding general purpose file systems are deleted.
Lifecycle management	A maximum of 20 lifecycle rules can be configured for a file system.
File locking with Flock	Not supported
Tag	A maximum of 20 tags can be added to a file system. Tag keys of a file system must be unique.

SFS Turbo

**Table 3** SFS Turbo restrictions
Item	General
Access method	VPN, Direct Connect, and Cloud Connect
Max. bandwidth	2 GB/s
Max. IOPS	100,000
Min. latency	1 to 2 ms
Max. capacity per file system	320 TB
Supported protocol	NFSv3
Max. number of clients per file system	500
Max. number of authorized VPCs per file system	20
Max. size of a single file	16 TB
Max. number of files or subdirectories per file system	1 billion
Max. number of files or subdirectories in a single directory	20 million NOTE: If you need to execute the ls, du, cp, chmod, or chown command on a directory, you are advised to place no more than 500,000 files or subdirectories in that directory. Otherwise, requests may take a long time to complete as the NFS protocol sends a large number of requests to traverse directory files and requests are queueing up.
Max. directory depth (unit: layer)	100
Max. path length (unit: byte)	1,024
Max. soft link length (unit: byte)	1,024
Max. hard link length (unit: byte)	255
Max. number of file systems	32 by default. You can submit a service ticket to increase the quota.
File system backup	Supported
Backup data restoring to the original file system	Not supported NOTE: SFS Turbo uses single-AZ deployment. SFS Turbo file systems will fail if their AZ fails.
File locking with Flock	Not supported
Cross-region mounting via domain name	Not supported NOTE: When you mount a file system using its domain name, cross-region mounting is not supported. To mount a file system across regions, mount the file system using IP address. The file system domain name randomly resolves to a corresponding domain name server IP address, so some domain name servers may have lots of mounts while others have only a few. It is recommended that you use the domain name servers to the maximum extent as uneven mounts may affect the file system performance.
Cache acceleration	Not supported
Tag	You can add a maximum of 10 tags to a file system. Tag keys of a file system must be unique.