Distributed File System & Cloud Storage

Distributed File System (DFS)

Definition:

• A DFS is a file system distributed across multiple servers or locations, allowing programs to access or store files as if they were local.

Purpose:

• Enables users of physically distributed systems to share data and resources using a common file system.

Key Features:

1. Transparency:
   • Location Transparency: Users don’t need to know the physical location of files.
   • Structure Transparency: No need for clients to know the number or locations of file servers.
   • Access Transparency: Local and remote files are accessible in the same manner.
   • Naming Transparency: File names do not indicate file locations.
   • Replication Transparency: Copies of files on multiple nodes are hidden from users.
2. User Mobility:
   • User’s home directory is automatically accessible from any node.
3. Performance:
   • Should be similar to that of a centralized file system.
4. Simplicity and Ease of Use:
   • Simple user interface with a small number of commands.
5. High Availability:
   • Continues to function in case of partial failures (link, node, or storage drive failures).
6. Scalability:
   • System grows easily as the number of nodes and users increase.
7. High Reliability:
   • Minimizes data loss with backup copies.
8. Data Integrity:
   • Ensures correct synchronization of concurrent access requests using concurrency control.
9. Security:
   • Implements mechanisms to safeguard information from unauthorized access.
10. Heterogeneity:
    • Supports multiple computer platforms.

File System Replication:

• Early iterations used Microsoft’s File Replication Service (FRS).
• Windows Server 2003 R2 introduced DFS Replication (DFSR), improving FRS by copying only changed portions of files and compressing data to minimize network traffic.

Standalone vs. Domain-based DFS Namespace:

• Standalone DFS Namespace: Exists on the local computer, not using Active Directory. Limited advantage and rarely used.
• Domain-based DFS Namespace: Stores DFS configuration in Active Directory, accessible via domain name.

Advantages:

• Allows multiple users to access/store data.
• Enhances data availability, access time, and network efficiency.
• Provides data transparency even if servers or disks fail.

Disadvantages:

• Security concerns due to the need to secure nodes and connections.
• Possible data/message loss during network movement.
• Complicated database connection and handling compared to single-user systems.
• Risk of overloading if all nodes send data simultaneously.

Cloud Storage

Definition:

• Cloud storage is a virtual locker for data, allowing remote storage and access through the internet.

Key Features:

1. Greater resource availability.
2. Easy maintenance.
3. Large network access.
4. Automatic systems.
5. Enhanced security.

Types of Storage Systems:

1. Block-Based Storage System:
   • Like traditional hard drives, allowing partitioning and formatting of volumes.
2. File-Based Storage System:
   • Accessed via a network, typically using NAS devices.
   • Pre-formatted and partitioned, mapped to local drive letters.
3. Object-Based Storage System:
   • Uses HTTP protocols for storing objects in containers without hierarchy.

Cloud Storage Architecture:

• Consists of distributed resources functioning as one.
• Durable through versioning and replication.
• Users pay based on actual usage, reducing capital expenses.
• Energy-efficient and secure, often disaster-proof.

Advantages:

• Scalability: Easy expansion of capacity and performance.
• Flexibility: Data manipulation and scaling according to needs.
• Simpler Data Migrations: Eliminates disruptive data migrations.
• Recovery: Access to files even if local hardware fails.

Disadvantages:

• Requires reliable electricity and internet.
• Limited support, especially for free versions.
• Dependency on internet connection.
• Slow networks can hinder access.

Benefits for Businesses:

• Saves space and money by eliminating on-premises data storage infrastructure.
• Simplifies hardware and software maintenance.
• Enhances employee collaboration and remote work capabilities.
• Reduces energy consumption, benefiting the environment.