Attaching and Mounting Existing Ebs Volume to Ec2 Instance Filesystem Issue

attaching a previous EBS Volume to a new EC2 Linux Instance

Yes, you can attach an existing EBS volume to an EC2 instance. There are a number of ways to do this depending on your tools of preference. I prefer the command line tools, so I tend to do something like:

ec2-attach-volume --instance-id i-XXXXXXXX /dev/sdh --device vol-VVVVVVVV

You could also do this in the AWS console:

https://console.aws.amazon.com/ec2/home?#s=Volumes

Right click on the volume, then select [Attach Volume]. Select the instance and enter the device (e.g., /dev/sdh).

After you have attached the volume to the instance, you will want to ssh to the instance and mount the volume with a command like:

sudo mkdir -m000 /vol2
sudo mount /dev/xvdh /vol2

You can then access your old data and configuration under /vol2

Note: The EBS volume and the EC2 instance must be in the same region and in the same availability zone to make the attachment.

Creating a file system on EBS volume, mounting it to EC2 instance and persisting data when instance is replaced with CDK

You almost got it - you just mount it and that's it. Formatting it does indeed wipe the data, the solution is simply to skip that step.

The docs you link to address this:

(Conditional) If you discovered that there is a file system on the device in the previous step, skip this step. If you have an empty volume, use the mkfs -t command to create a file system on the volume.

Warning.
Do not use this command if you're mounting a volume that already has data on it (for example, a volume that was created from a snapshot). Otherwise, you'll format the volume and delete the existing data.

So the following should work:

# mount the EBS volume
sudo mkdir /data  # make a directory on the EC2 machine
sudo mount /dev/sda1 /data  # mount the volume on the directory that was created

Mounting Old EBS Volume to the new Instance - Amazon EC2

What you need to do is mount the old volume on the new instance. Go to the Amazon EC2 control panel, and click "Volumes" (under Elastic Block Store). Look at the attachment information for the old EBS volume. This will be something like <instance id> (<instance name>):/dev/sdg

Make a note of the path given here, so that'd be /dev/sdg in the example above. Then use SSH and connect to your new instance, and type mkdir /mnt/oldvolume and then mount /dev/sdg /mnt/oldvolume (or whatever the path given in the control panel was). Your files should now be available under /mnt/oldvolume. If this does not solve your problem, please post again with the output of your df command after doing all of this.

So, to recap, to use an EBS volume on an instance, you need to attach it to that instance using the control panel (or API tools), and then mount it on the instance itself.

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