AWS EBS Multi-Attach

What is EBS Multi-Attach?

Amazon EBS Multi-Attach enables you to attach a single Provisioned IOPS SSD (io1 or io2) volume to multiple instances that are in the same Availability Zone. You can attach multiple Multi-Attach enabled volumes to an instance or set of instances. Each instance to which the volume is attached has full read and write permission to the shared volume. Multi-Attach makes it easier for you to achieve higher application availability in clustered Linux applications that manage concurrent write operations.

Limitations of EBS Multi-Attach:

There are a few limitations to be aware of when using Amazon Elastic Block Store (EBS) Multi-Attach volumes:

Only Nitro-based EC2 instances can use Multi-Attach volumes. This means that instances launched from certain older instance types or virtualization types will not be able to use Multi-Attach volumes
Multi-Attach volumes can only be attached to instances in the same availability zone. This means that you cannot use Multi-Attach to share a volume across multiple availability zones
Multi-Attach volumes can only be attached to instances that are in the running or stopped state. You cannot attach a Multi-Attach volume to an instance that is in the terminated state
Only certain types of workloads are suitable for Multi-Attach. High-performance workloads such as databases, big data, and HPC could be designed to use Multi-attach
Multi-Attach volumes can only be used with provisioned IOPS SSD (io1) and General Purpose SSD (gp2) volumes, and not with magnetic (standard) volumes
Multi-Attach volumes are currently only available in certain regions
The maximum IOPS and throughput limits per volume are lower when using Multi-Attach compared to when using a single-attach volume

Hands-on Lab Overview

The aim of this hands-on lab is to create EBS Multi-Attach and see it in action. We will create two EC2 instances (FirstInstance and SecondInstance) and one EBS volume with Multi-Attach enabled functionality. This EBS volume will be attached to the two EC2 instances. By accessing this EBS volume from one EC2 machine, we will format it, mount and create a file demoFile. We will access this file from the second EC2 machine. Then, we will create a file secondDemoFile on the second EC2 instance and access it from the first EC2 instance.

Hands-on Lab

Create an SSH key pair:
Create two EC2 instances with different AMIs: one with Ubuntu (AMI ID: ami-053b0d53c279acc90) and the second with Linux 2 (AMI ID: ami-09538990a0c4fe9be). Choose the instance type t3.small for both EC2 machines.
Then, create an EBS Multi-Attach volume:
Attach EBS Multi-Attach Volume to the two EC2 instances:
Check whether the volume was attached to the two EC2 instances:
Connect to the first EC2 instance above (FirstInstance) running Ubuntu via AWS EC2 Connect.

💡

IMPORTANT: Not all AMIs provided by AWS have EC2 Instance Connect integrated by default. The Amazon Linux 2 AMI and Ubuntu 20.04 or later come pre-configured with EC2 Instance Connect.

When the connection is established, list all available block devices on the instance to identify the block device that corresponds to your EBS volume:
```
 lsblk
```
As we can see as a result of lsblk command, there is no mount point for the attached EBS volume.
Format the EBS Volume:
```
 sudo mkfs.ext4 /dev/nvme1n1
```
Mount the EBS Volume:

Now, create a directory where you'll mount the volume:
```
sudo mkdir /mnt/myvolume
```
Mount the volume to this directory:
```
sudo mount /dev/nvme1n1 /mnt/myvolume
```
Connect to the second EC2 instance and identify the block device that corresponds to your EBS volume with the command lsblk.
Mount the EBS Volume:

Now, create a directory where you'll mount the volume and mount the volume to this directory:
Access the demoFile from the second EC2 instance:
Create another file secondDemoFile on the second EC2 instance:
Finally, to access secondDemoFile from the first EC2 instance, first, we need to unmount the EBS volume and mount it again to see the changes made by other instances.

Karlygash Yakiyayeva's Blog