Cloud Parallel File Storage:Limits

File system

Directory naming constraints

To ensure system stability and support for enterprise features, CPFS reserves some directory names. If you attempt to create a directory with a reserved name, the system returns an EPERM error. Reserved names fall into two categories:

• Reserved in the file system root directory only: The system returns the EPERM error only when you create a directory with a reserved name in the file system root directory. You can create directories with these names in other subdirectories.

• Reserved in any directory in the file system: The system returns the EPERM error when you create a directory with a reserved name at any level in the file system.

Supported operating systems

Fileset

• Fileset specification limits

  • Each file system supports up to 10 Filesets.

  • A Fileset can link to a directory up to 8 levels deep in a file system.

  • Each Fileset supports up to 1 million files or directories.

  • Nested Filesets are not supported.

Data flow

• Data flow specification limits

  • Each file system supports up to 10 data flows.

  • Each data flow supports up to 5 auto-update directories.

  • Each Fileset in a file system can be linked to only one OSS bucket.

  • Data flow task records are retained for a maximum of 90 days.

  • Data flow task reports are stored in the file system and consume storage space. A maximum of 1 million reports can be stored.

  • Cross-region data flows between a file system and an OSS bucket are not supported.

• Dataflow limits on file systems

  • In a fileset associated with a dataflow, do not rename a non-empty directory. Renaming a non-empty directory may result in a Permission Denied error or a "directory not empty" error.

  • Dataflows do not support Archive or Cold Archive objects in OSS.

  • Use special characters in directory and file names with caution. Supported characters include uppercase and lowercase letters, numbers, exclamation points (!), hyphens (-), underscores (_), periods (.), asterisks (*), and parentheses ().

  • Long paths are not supported. The maximum path length for a dataflow is 1,023 characters.

• Limits on data export

  • Dataflows do not support exporting hard links or symbolic links to an OSS bucket.

  • Dataflows do not support exporting empty directories to an OSS bucket.

  • Dataflows do not support exporting ChangeTime properties to an OSS bucket.

  • When a dataflow exports sparse data, zero-value holes are filled with padding before being exported to an OSS bucket.

Protocol service

• Protocol service specification limits

  Limits	Threshold	Description
  Protocol services per file system	1	One per file system.
  VPCs for publishing export directories	2	Up to two VPCs per protocol service.
  Export directories per protocol service	10	Up to 10 across filesets or directories.
  Mounted compute nodes per protocol service	10,000	Up to 10,000 per protocol service.
  Concurrently open files	150,000	No more files can open after this limit is reached.

• Other limits

  • Multiple clients can read and write files in a unified namespace. However, when multiple processes concurrently write the same file, write anomalies (overwrites, crossovers, serialization) may occur because NFSv3 does not support Atomic Append.

  • Network Lock Manager (NLM) is not supported.

  • NFSv4.x is not supported.