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I have an Amazon EC2 instance that has two EBS drives associated with it: an 8 GB drive at /dev/sda1, and a 20 GB drive at /dev/sdf. I didn't set this up so I'm not sure why this instance needs two drives of those sizes.

I'm trying to figure out which of these two EBS drives contains the root (/) volume. (My goal is to disconnect that drive and attach it to another instance, where I can gain access to a key file I need at /home/ec2-user/.ssh/authorized_keys, per this excellent answer.)

How can I tell? (What is /sda1 and /sdf?)

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up vote 1 down vote accepted

Just do a df -h. This will tell you if the 8G disk is mounted on / or the 20G one. Then just go to the EC2 web console and detach the disk.

"sda" term us usually used for SCSI drivers. I suggest you to read up a bit about Linux device files. It'll help you a lot.

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First, lets find the root device (probably it is /dev/sda1) with mount command. You will see your disk device with corresponding line where "on" is /.

Then you shoudl go to the AWS management console, EC2 section, find your instance, scroll down to the Block Devices section, then you'll see attached EBS Volumes to the intance and their IDs. Using this data you can find your Volume by its ID in the Volumes section.

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