Data Management Glossary
Global File System
A global file system, often referred to as a global distributed file system or a global namespace file system, is a type of file system that allows for the unified management and access of files and data across a distributed or networked environment. The goal is to abstract the physical location of files and provides a single, logical view of data regardless of where it is stored or how the storage is distributed. The concept of a global file system is commonly discussed in enterprise environments and cloud computing as a way to simplify data management, primarily unstructured data management, and improve accessibility.
Common features and characteristics of global file systems
- Unified Namespace: A global file system provides a single, unified namespace that abstracts the underlying storage infrastructure. Users and applications access files and data using a consistent naming convention, irrespective of the physical storage location.
- Distributed Data: Data within a global file system can be distributed across multiple storage devices, servers, data centers, or cloud services. This distribution can improve data availability, scalability, and fault tolerance.
- Access Transparency: Users and applications can access files and data without needing to know the physical location or storage details. This access transparency simplifies data access and management.
- Data Replication: Global file systems often support data replication to enhance data availability and redundancy. Copies of data can be stored in multiple locations for failover and disaster recovery purposes.
- Scalability: These file systems are designed to scale horizontally, allowing for the addition of storage devices or nodes to accommodate growing data requirements. A key issue with most so-called global file system or global namespace solution is that they sit in front of the hot data and become a data access and data performance bottleneck.
- Load Balancing: Load balancing mechanisms distribute data access requests across multiple servers or storage devices to optimize performance and prevent bottlenecks.
- Security: Security features, such as access controls, encryption, and authentication, are typically implemented to protect data within the global file system.
- Caching: Caching mechanisms can be employed to improve read and write performance by temporarily storing frequently accessed data in memory.
- Metadata Management: Metadata about files, such as file attributes, permissions, and access control lists, is managed centrally to ensure consistency.
- Versioning: Some global file systems support versioning, allowing users to access and restore previous versions of files.
- File Locking: File locking mechanisms may be implemented to prevent conflicts when multiple users or applications access the same file simultaneously.
- Compatibility: Global file systems are often designed to be compatible with various operating systems, file protocols, and APIs, making them versatile in heterogeneous environments.
Examples of global file systems and distributed file systems
- NFS (Network File System): NFSv4 and NFSv4.1 support a global namespace, enabling clients to access files across a network as if they were on a local file system.
- Ceph: Ceph is an open-source distributed storage platform that provides a global file system called CephFS, offering a unified namespace for object storage and block storage.
- GlusterFS: GlusterFS is a distributed file system that creates a single global namespace from multiple underlying storage servers.
- Amazon Elastic File System (EFS): EFS is a cloud-based global file system service provided by Amazon Web Services (AWS) that allows multiple Amazon EC2 instances to access shared file storage.
The promise of a global file system is to simplify data management in modern, distributed computing environments, making it easier for organizations to store, access, and manage their data resources efficiently and consistently across the network.
Global File System: Always in the Hot Data Path
A global file system provides a consistent way to access the data or metadata residing in that file system from many locations, and where multiple users in different locations may be working on copies of the same file. It also provides a consistent way to access, configure and administer the file system. The two types of global file systems are:
- Storage-centric: Stores the data and provides access to it using a single mount that fronts all data requests and is always in the hot data path. By “fronts all data” we mean that all data and metadata request are channeled through this mount. Some vendors extend this notion to keep the bulk of the data as proprietary blocks in the cloud. In this case of “cloud storage” GFS, you need to recognize that access to your data always requires licensing the GFS even when the bulk of your data may be in the cloud, which may unnecessarily add costs. A storage-centric GFS does not provide a truly global namespace. It can only provide visibility into data residing on that vendor’s storage system.
- Metadata-based: Also known as a virtual global file system, this approach fronts data sitting on other storage systems. All data and metadata access is channeled through this virtual global file system, which runs in front of existing storage file systems. The benefit of this approach is that it works across multiple storage vendors. However, there is a heavy price for this as all access must pass through the metadata-based controller, which slows down performance if it is implemented fully in software or increases costs substantially if it requires dedicated hardware. This is because it is in the hot data path and manages data access even though it is not storing any data blocks. A metadata-centric GFS can provide a global namespace across multi-vendor storage systems, but it must do so by fronting all data access, which will negatively impact performance and scalability.
A global file system enhances the inherent value of a storage solution when employees need to actively collaborate in use cases such as engineering collaboration and design. But since 80% of data is cold and not actively accessed, and since typically less than 5% of data requires active collaboration, for unstructured data management, data tiering and feeding data to AI/ML, a global namespace that is not in the hot data path gives truly heterogeneous visibility with the best performance.