How To Attach Single EBS To Multiple Instances?

Last Updated : 26 Feb, 2024

EBS Stands for Elastic Block Storage is a block-level storage service provided by Amazon web services to use with Amazon’s Elastic Compute Cloud (EC2) instances.It provides persistent, high-performance storage volumes that can be attached to Amazon EC2 instances. it acts as an attached external hard drive to your instances. These EBS Volumes can be dynamically scaled to accommodate changing storage requirements. users can increase the size of a volume without detaching it from the instance, enabling them to scale storage capacity on-demand as they need.

Features of Elastic Block Service (EBS)

Block-level storage: EBS provides block-level storage volumes, which can be attached to EC2 instances as devices similar to physical external hard drives.
Elasticity: EBS volumes can be easily scaled up or scaled down based on users’ storage requirements, providing scalability and flexibility.
Performance-Based Volume Types: EBS offers different volume types optimized for various workloads, including:
- General Purpose SSD (gp2/gp3): Suitable for normal workloads with a balance of price and performance.
- Provisioned IOPS SSD (io1/io2): Designed for I/O-intense workloads requiring consistent and predictable performance.
- Throughput Optimized HDD (st1): It is for large, continuous workloads such as data warehouses and log processing.
- Cold HDD (sc1): Frequently used for less frequently accessed workloads with large volumes of data.
Snapshot and Backup: EBS allows users to create point-in-time snapshots of their volumes, which can be used for backup, disaster recovery purposes etc.
High Availability and Durability: EBS volumes can be copied within an Availability Zone (AZ) to ensure high availability and durability. Additionally, you can create snapshots that are stored in Amazon S3 across multiple AZs for enhanced availability.

Step-By-Step Guide to Attach Single EBS To Multiple Instances

Note: AWS Provides attached features io1 and io2 volume types other types of volumes are not supported with this feature also io1 volume type is supported only in regions S East (N. Virginia), US West (Oregon), and Asia Pacific (Seoul). However, io2 is supported in almost all regions so in this guide we are going to io2 volume type.

Step 1: Open the Amazon EC2 console at “https://console.aws.amazon.com” and log in. To know how to create an AWS Free tier account refer to the Amazon Web Services (AWS) – Free Tier Account Set up.

Step 2: In the dashboard type EC2 and go to the volumes tab

EC2 Dash board

Step 3: In volume section click on create volume, in that select your volume type as Provisioned IOPS SSD (io2) change your volume size and iops as per your requirements or otherwise continue with what by default is selected. Select your Availability Zone same as your instances are running in also you can create your Snapshot ID (optional)

Important : Make sure you checked in Enable Multi-Attach option

volum1

You can encrypt your volume if needed.After completing all the options click on create volume button

volum2

Step 4: After Creating the volume click on attach volume

Note: Make sure at least two instances should be running to achieve this multi attach goal.

attach-volume

Step 5: Now select your instances to attach to this volume and click on attach volume.Repeat this same step for second instance as well

attach-volume

you attached the single EBS to multiple instances

Advantages of EBS (Elastic Block Storage)

Simple to Manage: EBS integrates seamlessly with Amazon EC2 instances and other AWS services for a smooth user experience. user can gain insights into volume performance and its usage details with detailed monitoring
Cost Optimized: EBS Follows Pay-as-you-go model user have to Only pay for the storage they use, making it cost-effective. Different volume types comes with different performance and cost needs, allowing user to choose the most economical option for their workload.
High Performance: EBS delivers low latency and high throughput for demanding applications, ensuring smooth performance.
Developers Productivity: Developers can manage EBS volumes programmatically through the AWS Command Line Interface (CLI) or API for automation and integration with DevOps operations

Disadvantages of EBS (Elastic Block Storage)

EBS Volumes cannot be attached to the ec2 instance which is in different region than the EBS volumes are. means EBS volumes and EC2 instances must be in same region.
Some Instance Types does not support certain types of EC2 instances. like Provisioned IOPS (io1) volumes may be not supported some instance types
An EC2 instance can only be attached to a limited number of EBS volumes, and the maximum number of volumes depends on the instance type.
Attaching and detaching EBS volumes may incur some downtime or affect the performance of the instance, especially if the volume is heavily utilized.
There may be costs associated with data transfer between EC2 instances and attached EBS volumes, especially if the EC2 instance and EBS volume are in different Availability Zones within the same region.

Challenges of Multi-Instance Attachment

Concurrency & Consistency Challenge: EBS volumes are designed to be attached to a single EC2 instance at a time. Attaching the same EBS volume to multiple instances introduces concurrency issues and can lead to data corruption or inconsistency.
Network Challenges: EBS volumes are network based storage device that communicate with EC2 instances over the network, therefore when multiple instances uses single EBS volume. the network bandwidth is highly used resulting into high latency and decrease in network performance
Data Integrity Challenges: sharing access to the same EBS volume across multiple instances highly increases the risk of data corruption and integrity issues. Concurrent read and write operations from multiple instances on one EBS volume leads to unintended data modifications
High Availability and Fault Tolerance Challenge: EBS volume can be attached to a multiple EC2 instances within a same availability zone only. multi-instance cannot be designed to achieve high availability or fault tolerance. as the EBS volume residing in a one availability zone cannot be attached to multiple instances with other availability zone
Performance Issues: EBS volumes has certain limits in terms of IOPS (Input Output Per Second) When multiple instances share access to the same EBS volume they are highly utilized because of this high utilization it leads to performance issues of EBS volumes.

Basic Examples of Elastic Block Storage

1. Attaching EBS Volume to an EC2 Instance

Lets say user have an EC2 instance running a web server, and it wants to add additional storage for storing website data. to achieve this user can create an EBS volume and attach it to its EC2 instance. Once attached, the EBS volume appears as a block storage device on EC2 instance

2. Creating Snapshots for Backup

User want to create backups of your EBS volumes to protect against data loss or corruption. it can create snapshots of your EBS volumes using the AWS Management Console, CLI, or SDKs. These snapshots stores the volume’s data at a specific point in time and are stored in Amazon S3, providing durability and reliability. user can then use these snapshots to restore your volumes or create new volumes in case of failures.

3. Using EBS Multi-Attach for Shared Storage

User have a distributed application running on multiple EC2 instances that need to access shared data simultaneously. it can use Certain EBS volume types, such as io1/io2, support multi-attach, allowing them to attach a single volume to multiple EC2 instances within the same AZ. This enables to create shared storage without the need for complex clustering solutions. Each EC2 instance can read and write data to the shared volume, making it suitable for scenarios like shared file systems or database storage.

4. Encryption of EBS Volumes

User need to ensure that your data stored on EBS volumes is encrypted to meet compliance requirements. EBS volumes support encryption using AWS Key Management Service (KMS). user can enable encryption when creating a new volume or encrypt existing volumes using AWS Management Console, CLI, or SDKs.

Applications of Single EBS Volume to Multi-Instance Attachments

Shared Data Cluster: In some cases, users may have a requirement to share read only data across multiple EC2 instances. for example you might have a large dataset that needs to be processed. to reduce time consumption it can be achieved by creating cluster of multiple instances by sharing it on single EBS volume. However, it’s essential to ensure that the data is not modified by any of the instances to maintain data integrity.
Distributed Computing: User might implement a distributed file system on top of a shared EBS volume to provide shared storage across multiple instances. Distributed file systems like NFS (Network File System) can be configured to use an EBS volume as shared storage accessible by multiple instances.
Temporary Storage for Stateless Applications: In some cases, user may have a need of temporary storage space across multiple instances. For example, users might have a batch processing job that requires temporary storage for immediate results A shared EBS volume could be used for this purpose, with appropriate cleanup mechanisms in place to reclaim space after the job is complete.
Centralized Storage: Attaching a single EBS volume to multiple instances can also be used for centralized storage for example, users might use a shared EBS volume to store logs generated by multiple EC2 instances in a centralized location. This could simplify log management by storing logs from multiple instances in one place

Conclusion

Attaching a single Elastic Block Store (EBS) volume to multiple instances is not a typical or recommended configuration in Amazon Web Services (AWS). EBS volumes are designed to be attached to a single Amazon EC2 instance at a time. Each volume is associated with a specific instance to provide block-level storage for that instance.