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volumes

GCP Display Device Names on OS

In GCP console you can see the VM’s Device Names. In this case, it’s boot and persistent-disk-1.

Name		          Device name
server-boot               boot	
server-data               persistent-disk-1

To display the volume names on the OS, run this command.

$ ls -l /dev/disk/by-id
total 0
lrwxrwxrwx. 1 root root  9 Aug  2 01:12 google-boot -> ../../sda
lrwxrwxrwx. 1 root root 10 Aug  2 01:12 google-boot-part1 -> ../../sda1
lrwxrwxrwx. 1 root root  9 Aug 18 18:48 google-persistent-disk-1 -> ../../sdb
lrwxrwxrwx. 1 root root  9 Aug  2 01:12 scsi-0Google_PersistentDisk_boot -> ../../sda
lrwxrwxrwx. 1 root root 10 Aug  2 01:12 scsi-0Google_PersistentDisk_boot-part1 -> ../../sda1
lrwxrwxrwx. 1 root root  9 Aug 18 18:48 scsi-0Google_PersistentDisk_persistent-disk-1 -> ../../sdb

As you can see, boot and persistent-disk-1 are displayed along with its device names /dev/sda and /dev/sdb.

AWS XFS Volume Setup

Here’s how to setup a XFS volume.

file -s /dev/nvme2n1
mkfs -t xfs /dev/nvme2n1

Mount to /data.

mkdir /data
mount /dev/nvme2n1 /data

Add to /etc/fstab.

vim /etc/fstab
#
#
UUID=xxxxxxxxxxxxxxxxxxxxxx /data  xfs  defaults 0 0

Nitro-based Instance Volumes

AWS introduced Nitro-based instances which are modular. They are meant for high performance, high availability, and high security systems. Nitro building blocks provide direct access to high-speed local storage over a PCI interface and transparently encrypts all data using dedicated hardware. It also provides hardware-level isolation between storage devices and EC2 instances so that bare metal instances can benefit from local NVMe storage. The following are Nitro-based instances: A1, C5, C5d, C5n, I3en, M5, M5a, M5ad, M5d, p3dn.24xlarge, R5, R5a, R5ad, R5d, T3, T3a, and z1d. Bare metal: c5.metal, c5n.metal, i3.metal, i3en.metal, m5.metal, m5d.metal, r5.metal, r5d.metal, u-6tb1.metal, u-9tb1.metal, u-12tb1.metal, and z1d.metal.

Although Nitro-based instances looks like regular volumes (/dev/xvda) from the AWS Console, inside the operating system, they look (/dev/nvme6n1) completely different.

In AWS Console, the storage devices will look like this.

/dev/sda1
/dev/xvdb
/dev/xvdc
/dev/xvdd
/dev/xvde
/dev/xvdh
/dev/xvdf
/dev/xvdi
/dev/xvdg
/dev/xvdj

In the operating system, invoking df -h, results in this.

/dev/nvme0n1p2   30G  7.0G   24G  24% /
/dev/nvme4n1     50G   20G   31G  40% /vol1
/dev/nvme1n1     10G  753M  9.3G   8% /vol2
/dev/nvme8n1    500G   67G  433G  14% /backups
/dev/nvme2n1    400G   12G  388G   3% /vol3
/dev/nvme6n1    150G  150G  755M 100% /vol4
/dev/nvme7n1     10G   33M   10G   1% /vol5
/dev/nvme5n1     10G  553M  9.5G   6% /vol6
/dev/nvme9n1    100G   91G   10G  91% /vol7

The big question is, how can you tell which volume is associated with which. You’ll need nvme program to map out the volumes. Install nvme-cli first.

yum install nvme-cli

Then run the command below.

# run nvme
sudo nvme id-ctrl -v /dev/nvme6n1 | grep xv
# the result
0000: 2f 64 65 76 2f 73 64 6a 20 20 20 20 20 20 20 20 "/dev/xvdf..."

Steps to Encrypt Volumes

Here the steps to encrypt an unencrypted volume.

  1. Take a snapshot of the unencrypted volume.
  2. Make a copy of that snapshot and turn on encryption.
  3. Create a volume of the encrypted snapshot.
  4. Stop the instance.
  5. Detach the original unencrypted volume from the instance.
  6. Attach the newly created encrypted volume to the instance.
  7. Start the instance.

AWS CLI

# CREATE A SNAPSHOT
aws ec2 create-snapshot \
--volume-id vol-1234567890abcdef0 \
--description "This is my snapshot"
 
# COPY SNAPSHOT
aws ec2 copy-snapshot \
--source-region us-west-2 --source-snapshot-id snap-066877671789bd71b \
--region us-east-1 --description "This is my copied snapshot."
 
# CREATE A VOLUME
aws ec2 create-volume \
--region us-east-1 --availability-zone us-east-1a \
--snapshot-id snap-066877671789bd71b --volume-type io1 --iops 1000
 
# STOP AN INSTANCE
aws ec2 stop-instances --instance-ids i-1234567890abcdef0
 
# DETACH A VOLUME
aws ec2 detach-volume --volume-id vol-1234567890abcdef0
 
# ATTACH A VOLUME
aws ec2 attach-volume --volume-id vol-1234567890abcdef0 \
--instance-id i-01474ef662b89480 --device /dev/sdf
 
# START AN INSTANCE
aws ec2 start-instances --instance-ids i-1234567890abcdef0

Print Block Device Attributes

Everything you need to know about block devices, e.g. UUID

blkid
# or
blkid /dev/xvda

You can also run file -s. You need to be root.

file -s /dev/xvda1

EC2 Describe Snapshots

If you have a ton of snapshots, they tend to be difficult to find within the AWS console. Although AWS has optimized the snapshot view, it’s still in beta. Filtering a volume id is still a problem. It might be faster just to use the AWS CLI to display snapshot information. Here’s an example of how to display snapshots given a certain volume id.

aws ec2 describe-snapshots \
--filters Name=volume-id,Values=vol-xxxxxxxxxxxxxx \
--query "Snapshots[*].{ID:SnapshotId,Time:StartTime,Progress:Progress}" \
--profile default

The result is something like this.

{
        "Progress": "99%",
        "ID": "snap-xxxxxxxxxxxxxxx",
        "Time": "2018-12-25T10:19:51.385Z"
    },
    {
        "Progress": "99%",
        "ID": "snap-xxxxxxxxxxxxxxx",
        "Time": "2018-12-24T09:35:09.357Z"
    }