Notes and Constraints

SFS Capacity-Oriented

**Table 1** SFS Capacity-Oriented restrictions
Item	Description
Access method	Can only be accessed over the intranet and used on the cloud.
Supported protocols	Only NFSv3 is supported (NFSv4 is not supported). 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 general purpose file systems allowed	You can create a maximum of 10 general purpose file systems with one account.
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	1 billion
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 12 hours 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	Standard, Standard – Enhanced, Performance, and Performance – Enhanced	20 MB/s/TiB, 40 MB/s/TiB, 125 MB/s/TiB, 250 MB/s/TiB, 500 MB/s/TiB, and 1,000 MB/s/TiB
Access methods	VPN, Direct Connect, and Cloud Connect	VPN, Direct Connect, and Cloud Connect
Max. bandwidth	Standard: 150 MB/s Standard-Enhanced: 1 GB/s Performance: 350 MB/s Performance-Enhanced: 2 GB/s	20 MB/s/TiB and 40 MB/s/TiB: 8 GB/s (You can submit a service ticket to get up to 20 GB/s of throughput.) 125 MB/s/TiB and 250 MB/s/TiB: 20 GB/s (You can submit a service ticket to get up to 100 GB/s of throughput.) 500 MB/s/TiB and 1,000 MB/s/TiB: 80 GB/s
Max. IOPS	Standard: 5,000 Standard-Enhanced: 15,000 Performance: 20,000 Performance-Enhanced: 100,000	20 MB/s/TiB and 40 MB/s/TiB: 250,000 125 MB/s/TiB and 250 MB/s/TiB: 1 million 500 MB/s/TiB and 1,000 MB/s/TiB: 4 million
Min. latency	1 to 2 ms	1 to 2 ms
Max. capacity of a file system	Standard and Performance: 32 TB Standard-Enhanced and Performance-Enhanced: 320 TB	1 PB
Supported protocol	NFSv3 only	NFSv3 only
Max. number of clients that a file system allows	500	3,000
Max. number of authorized VPCs per file system	20	20
Max. size of a single file	16 TB	320 TB
Max. number of files or subdirectories per file system	1 billion NOTE: The number of files or subdirectories allowed in a single file system is calculated by dividing the total capacity (KB) by 16. If the calculated value is greater than 1 billion, the number of files or subdirectories allowed is 1 billion.	2 billion NOTE: The number of files or subdirectories allowed in a single file system is calculated by multiplying the total capacity (GB) with 25,000. If the calculated value is greater than 2 billion, the number of files or subdirectories allowed is 2 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 queue for a long time as the NFS protocol needs to send a large number of requests to traverse files in the 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 queue for a long time as the NFS protocol needs to send a large number of requests to traverse files in the directory.
Max. directory depth (unit: level)	100	100
Max. path length (unit: byte)	1,024	4,096
Max. soft link length (unit: byte)	1,024	1,024
Max. hard link length (unit: byte)	255	255
Max. number of file systems	32 by default. You can submit a service ticket to increase the quota.	32 by default. You can submit a service ticket to increase the quota.
File system backup	Supported	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.	Not supported
File locking with Flock	Not supported	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.	Not supported
Cache acceleration	Not supported	Supported. (Eventual consistency only. To disable cache acceleration, submit a service ticket.) NOTE: When multiple clients access the same file system, access requests of the same client may be routed to different background nodes. Eventual consistency means that if a request hits a node's local cache, it will fail to obtain the modifications made by other clients. Cache is usually valid for 3 to 30 seconds.
Tag	A maximum of 20 tags can be added to a file system. Tag keys of a file system must be unique.