Understanding Amazon EBS: Persistent Storage for EC2 Instances

Understanding Amazon EBS: Persistent Storage for EC2 Instances

Amazon EBS (Elastic Block Store) is a critical component of AWS’s EC2 (Elastic Compute Cloud) service, providing durable, block-level storage for virtual servers. It enables data persistence, flexible volume management, and seamless integration with EC2 instances, making it indispensable for cloud computing workflows.

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What is EBS?

• Definition: EBS is AWS’s block storage service that functions like a “network-connected USB drive,” allowing EC2 instances to store and retrieve data persistently.
• Purpose: Ensures data remains accessible even after an EC2 instance is stopped or terminated. Ideal for databases, logs, and application data.
• Impact: Eliminates the need for local storage, enabling scalable, on-demand storage solutions.

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Key Features of EBS

1. Data Persistence

• Function: Retains data even if the EC2 instance is stopped or terminated (unless configured otherwise).
• Use Case: Critical for applications requiring data durability, such as databases or stateful services.
• Metric: No data loss by default (unless “Delete on Termination” is enabled).

2. Zone Affinity and Snapshots

• AZ Alignment: Volumes are tied to a specific Availability Zone (AZ) (e.g., us-east-1a). Direct cross-AZ attachment is not possible.
• Snapshot Workaround:
  • Snapshots (point-in-time backups) can be created to migrate volumes to other AZs.
  • Snapshots are stored in S3 and can be used to create new volumes in different AZs.
• Impact: Enables disaster recovery and multi-AZ redundancy strategies.

3. Volume Management

• Flexibility:
  • Volumes can be detached from one EC2 instance and reattached to another.
  • Supports multiple volumes per instance (e.g., root volume + data volumes).
• Limitation: A single volume can only be attached to one instance at a time (basic EC2 level).
• Use Case: Facilitates failover, maintenance, and data migration.

4. Performance Metrics

• IOPS (Input/Output Operations Per Second):
  • Determines volume performance; higher IOPS = faster data access.
  • Example: General-purpose volumes (e.g., gp3) offer 3,000 IOPS baseline, while provisioned IOPS (e.g., io1) allow up to 64,000 IOPS.
• Latency: Slight network-induced delay, but negligible for most applications with proper volume selection.

5. Provisioning and Cost

• Configuration:
  • Size: Defined in gigabytes (e.g., 100 GB, 1 TB).
  • IOPS: Configurable during creation or later (e.g., 1,000 IOPS for high-performance workloads).
• Billing: Charged based on provisioned capacity, not actual usage (e.g., $0.10 per GB-month for gp3 volumes).

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Critical Configuration: Delete on Termination

• Purpose: Controls whether a volume is deleted when its EC2 instance is terminated.
• Behavior:
  • Enabled: Volume is deleted with the instance (default for root volumes).
  • Disabled: Volume persists after termination (recommended for data retention).
• Example:
  • Root volume: Delete on Termination = Enabled (default).
  • Data volume: Delete on Termination = Disabled (to preserve backups).

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Summary Table of Key Concepts

Concept	Meaning	Dive
EBS	AWS block storage for EC2; acts as a network-connected drive.	Ensures data persistence and flexibility.
Persistência	Data remains after EC2 termination.	Ideal for databases, logs, and stateful apps.
AZ Alignment	Volumes are tied to a specific AZ.	Use snapshots for cross-AZ migration.
IOPS	Measures volume performance (e.g., 3,000 IOPS for gp3).	Higher IOPS = faster access for databases or analytics.
Delete on Termination	Controls volume deletion when EC2 instance is terminated.	Disable for critical data; enable for temporary workloads.

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Real-World Applications

• Database Hosting: Use high-IOPS volumes (io1) for relational databases (e.g., MySQL, PostgreSQL).
• Data Backup: Create snapshots for disaster recovery and cross-AZ redundancy.
• Cost Optimization: Choose gp3 volumes for general workloads and disable “Delete on Termination” for critical data.

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Reference

https://dev.to/sinngjpeg/ebs-entendendo-o-armazenamento-do-ec2-2bgf