Block storage vs object storage vs file storage in HLD - Architecture Patterns Compared

System Overview - Block storage vs object storage vs file storage

This system explains three common types of data storage: block storage, object storage, and file storage. Each type stores data differently and is suited for different use cases like databases, backups, or shared files.

Architecture Diagram

User
  |
  v
+-----------------+       +-----------------+       +-----------------+
| Block Storage   |<----->| File Storage    |<----->| Object Storage  |
| (Raw Data Blocks)|       | (Hierarchical)  |       | (Metadata + Data)|
+-----------------+       +-----------------+       +-----------------+

Components

Block Storage

storage

Stores raw data in fixed-size blocks, ideal for databases and virtual machines.

File Storage

storage

Stores data as files in folders with a hierarchy, suitable for shared file systems.

Object Storage

storage

Stores data as objects with metadata and unique IDs, good for backups and large unstructured data.

Request Flow - 3 Hops

User → Block Storage

User → File Storage

User → Object Storage

Failure Scenario

Component Fails:Block Storage

Impact:Data blocks may become inaccessible or corrupted, affecting databases or VMs.

Mitigation:Use replication and backups; implement RAID or distributed block storage systems.

Architecture Quiz - 3 Questions

Which storage type stores data as fixed-size blocks without metadata?

A Block Storage

B File Storage

C Object Storage

D Cloud Storage

Design Principle

This architecture shows how different storage types serve different needs by organizing and accessing data differently: block storage for low-level fast access, file storage for shared hierarchical files, and object storage for scalable metadata-rich data.

Practice

1. Which storage type splits data into fixed-size blocks and provides fast, low-level access?

easy

A. Block storage

B. Object storage

C. File storage

D. Cloud storage

Solution

1. Step 1: Understand block storage concept

   Block storage divides data into blocks and stores them separately for quick access.

2. Step 2: Compare with other storage types

   Object storage stores data as objects with metadata, and file storage organizes data in files and folders.

3. Final Answer:

   Block storage -> Option A

4. Quick Check:

   Block storage = fast block-level access [OK]

Hint: Blocks mean fast raw data access, not files or objects [OK]

Common Mistakes:

• Confusing object storage with block storage
• Thinking file storage splits data into blocks
• Assuming cloud storage is a type here

2. Which of the following correctly describes object storage?

easy

A. Stores data as blocks without metadata

B. Stores data as objects with metadata for easy retrieval

C. Organizes data in hierarchical files and folders

D. Splits data into fixed-size chunks for fast access

Solution

1. Step 1: Recall object storage features

   Object storage saves data as objects, each with metadata describing the data.

2. Step 2: Eliminate incorrect options

   Blocks without metadata describe block storage; hierarchical files describe file storage.

3. Final Answer:

   Stores data as objects with metadata for easy retrieval -> Option B

4. Quick Check:

   Object storage = objects + metadata [OK]

Hint: Objects always have metadata; blocks do not [OK]

Common Mistakes:

• Mixing block storage with object storage
• Thinking file storage uses metadata like objects
• Confusing hierarchical files with object storage

3. A company needs to store large amounts of unstructured data like images and videos with metadata for easy search. Which storage type fits best?

medium

A. Object storage for metadata and scalability

B. Block storage for fast raw access

C. File storage for hierarchical organization

D. Local disk storage for simplicity

Solution

1. Step 1: Analyze data type and requirements

   Unstructured data like images/videos benefit from metadata and scalability.

2. Step 2: Match storage type to needs

   Object storage supports metadata and scales well for large unstructured data sets.

3. Final Answer:

   Object storage for metadata and scalability -> Option A

4. Quick Check:

   Unstructured + metadata = Object storage [OK]

Hint: Metadata + large unstructured data = object storage [OK]

Common Mistakes:

• Choosing block storage for unstructured data
• Assuming file storage handles metadata well
• Picking local disk which lacks scalability

4. A developer tries to use file storage for a distributed app needing fast block-level access but experiences slow performance. What is the likely cause?

medium

A. File storage does not support hierarchical folders

B. Block storage cannot be used in distributed apps

C. File storage is not optimized for block-level raw access

D. Object storage lacks metadata support

Solution

1. Step 1: Understand file storage characteristics

   File storage organizes data in files and folders, optimized for sharing, not raw block access.

2. Step 2: Identify mismatch with app needs

   Fast block-level access requires block storage, not file storage, causing slow performance.

3. Final Answer:

   File storage is not optimized for block-level raw access -> Option C

4. Quick Check:

   File storage ≠ fast block access [OK]

Hint: File storage is for files, not fast block access [OK]

Common Mistakes:

• Believing block storage can't be used distributed
• Confusing object storage metadata with file storage
• Thinking file storage lacks folders

5. You are designing a scalable photo-sharing app. Users upload photos with tags and descriptions. Which storage type should you choose and why?

hard

A. Local disk storage, for simplicity and speed

B. File storage, to organize photos in folders by user

C. Block storage, for fast access to photo bytes

D. Object storage, to store photos with metadata and scale easily

Solution

1. Step 1: Analyze app requirements

   The app needs to store photos with tags/descriptions (metadata) and scale for many users.

2. Step 2: Match storage type to requirements

   Object storage supports metadata per object and scales well for large data and users.

3. Step 3: Evaluate other options

   Block storage is low-level without metadata; file storage is less scalable; local disk lacks scalability and reliability.

4. Final Answer:

   Object storage, to store photos with metadata and scale easily -> Option D

5. Quick Check:

   Photo app + metadata + scale = Object storage [OK]

Hint: Metadata + scale = object storage for apps [OK]

Common Mistakes:

• Choosing block storage ignoring metadata needs
• Assuming file storage scales well for many users
• Picking local disk for a cloud-scale app