Distributed file systems can share data from a single computer system among multiple servers, so that client systems can use multiple storage resources as if it were local storage. Distributed file systems allow organizations to access data in an easily scalable, secure, and convenient way.
A DFS allows direct host access to file data from multiple locations. For example, NFS is a type of distributed file system protocol where storage resources connect to a computer through network resources, such as a LAN or SAN. Hosts can access data using protocols such as NFS or SMB. Administrators can add nodes to a DFS to scale quickly. A DFS must create backup copies to prevent data loss in the event of a disk failure.
Distributed File System Features
There are various features for a DFS, such as the following:
- Transparency. Transparency is a security mechanism that protects the details of a file system from other file systems and users. There are four types:
- Structure transparency. The actual structure of DFS, such as the number of file servers and storage devices, is hidden from users.
- Access transparency. The DFS should display the user’s file resources following the correct secure login process, regardless of the user’s location.
- Replication transparency. Replicated files stored in different DFS nodes are hidden from other file system nodes.
- Name transparency. File names should not indicate the location of a given file and should not change as files move between DFS-supported storage nodes.
- Performance. This metric measures the time it takes to process user file access requests and includes CPU time, network transmission time, and the time it takes to access the storage device and deliver the requested content. DFS performance should be comparable to that of a local file system.
- Scalability. As storage needs increase, users typically deploy additional storage resources. DFS must be powerful enough that as storage capacity increases, the system can handle the additional resources so that users do not notice any performance difference.
- High availability. Like any storage device, devices managed by a DFS should not be interrupted or disabled. However, if a problem such as a node failure or disk failure occurs, the DFS must remain operational and quickly reconfigure for other storage resources to maintain uninterrupted operations. Disaster recovery plans should include provisions for backing up and restoring DFS servers, as well as storage devices.
- Data Integrity. When multiple users access the same file storage systems and possibly the same files, the DFS must manage the flow of access requests so that there is no interruption in file access or damage to file integrity.
- Great reliability. Another way to ensure data availability and survivability in the event of a disruption is to have the DFS create backup copies of user-specified files. This is complementary to high availability and ensures that files and databases are available when needed.
- Security. As with any data storage arrangement, data must be protected against unauthorized access and cyberattacks that could damage or destroy the data. Encrypting data, at rest and in transit, helps strengthen data security and protection.
- User mobility. This feature routes a user’s file resource directory to the node to which the user logs in.
- Namespaces. namespace defines a repository of commands and variables to facilitate specific activities. In distributed file systems, namespaces collect required commands and associated actions necessary for DFS to function properly. A single namespace supporting multiple file systems generates a single user interface that makes all file systems look like a single file system to a user. Namespaces also reduce the risk of interference with content from other namespaces.
Autonomous DFS versus domain-based DFS Namespaces
Stand-alone distributed file systems do not use Active Directory (AD). Instead, they are created locally with their own unique root directories. They cannot be linked to any other DFS entity. They are not as popular as domain-based distributed file systems.
Domain-based DFS namespaces store the configuration of a DFS in AD. This makes DFS easier to use and more accessible across an entire system.
Strengths and Limitations of Distributed File Systems
DFS technology provides file survivability by distributing critical files and databases across multiple storage devices. Some of these storage entities are in other company locations and may also be cloud-based, providing additional DR support. Users can improve the movement of data between storage nodes.
Difficulties may arise when modifying file servers, file storage applications, and other storage protocols that may not be compatible with the DFS/NFS application. There are risks of data loss if security arrangements are not in place. Additionally, moving data from one storage node to another can lead to data loss.
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