AWS – EBS – Exam Tips

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An Amazon EBS volume is a block-level storage device that you can attach to a single EC2 instance. Like a virtual hard disk, this can host the instance operating systems, database as well as system and data files. You can use it like a physical hard drive attached to your servers in the AWS Cloud.

Amazon EBS provides the following volume types:

  • General Purpose SSD (gp2)
  • Provisioned IOPS SSD (io1)
  • Throughput Optimized HDD (st1)
  • Cold HDD (sc1)
  • Magnetic (standard).

Key Features of EBS Volumes

  • Data Durability – EBS Volumes are automatically replicated within the availability zone it was created in to prevent data loss due to hardware failures. In addition, volumes can be attached as native block devices similar to physical hard drives and the instance can interact with the volume including formatting the volume with a file system and installing applications. You can stripe data across the volumes for increased I/O and throughput performance
  • Data Persistence – EBS Volumes can exist independently of any server instance similar to virtual hard disks that can be attached to Virtual Machines. By default, EBS volumes that are attached to a running instance automatically detach from the instance with their data intact when that instance is terminated. This is except where you have the root volume attached when you launch the instance and the ‘Delete on Termination’ checkbox is ticked.  In addition, with EBS backed instances, you can stop and restart that instance without affecting the data stored in the attached volume.
  • Data encryption – You can create encrypted EBS volumes with the encryption option available when creating new volumes. Amazon EBS encryption uses 256-bit Advanced Encryption Standard algorithms (AES-256) and an Amazon-managed key infrastructure. You can use a customer master key (CMK) for your EBS volumes too.
  • Snapshots – You can create a point in time snapshot of any EBS volumes to store backups of your data. Snapshots are stored in Amazon S3, with redundancy across multiple Availability Zones. In addition, you can create periodic snapshots of the volume which are incremental backups of the data. Snapshots can be used to create multiple new EBS volumes, expand the size of a volume, or move volumes across Availability Zones. Snapshots of encrypted EBS volumes are automatically encrypted. Snapshots can also be shared between AWS accounts or made publicly available.If you need to create a snapshot of a volume that is being us as a boot/root device, you must first stop the instance before taking the snapshot. If you don’t. Amazon will automatically stop the instance when you attempt to take the snapshot and as such, it would be advisable to plan a schedule for taking such snapshots in live production environments.

 

Encrypting snapshots

  • Snapshots of encrypted volumes are automatically encrypted.
  • Volumes that are created from encrypted snapshots are automatically encrypted.
  • When you copy an unencrypted snapshot that you own, you can encrypt it during the copy process.
  • When you copy an encrypted snapshot that you own, you can re-encrypt it with a different key during the copy process.

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