Storage and Databases

Instance stores and Amazon Elastic Book Store (Amazon EBS)

Block-level storage volumes behave like physical hard drives. An instance store provides temporary block-level storage for an Amazon EC2 instance. An instance store is disk storage that is physically attached to the host computer for an EC2 instance, and therefore has the same lifespan as the instance. When the instance is terminated, any data in the instance store is lost. See below :

Amazon EC2 instance with an attached instance store is running
Amazon EC2 instance is stopped or terminated
All data on the attached Amazon EC2 instance is deleted

Amazon Elastic Block Store (Amazon EBS) is a service that provides block-level storage volumes that can be used with Amazon EC2 instances. If Amazon EC2 instance is stopped or terminated, all the data on the attached EBS volume remains available. To create an EBS volume, company defines the configuration (such as volume size and type) and provisions it. After an EBS volume is created, it can be attached to an Amazon EC2 instance.

Because EBS volumes are for data the needs to persist, it’s important to back up the data. Company can take incremental backups of EBS volumes by creating Amazon EBS snapshots :

Amazon EBS snapshots

An EBS snapshot is an incremental backup. This means that the first backup taken of a volume copies all the data. For subsequent backups, only the blocks of data that have changed since the most recent snapshot are saved.

Incremental backups are different from full backups, in which all the data in a storage volume copies each time a backup occurs. The full backup includes data that has not changed since the most recent backup.


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