Block storage, is the term used for non-elastic storage and is a vital component of many other services of the cloud. Most commonly, block storage is used by virtual servers in the form of volumes, which behave similarly to how disks attach to a physical server. They are expected to be used with filesystems or storage support inside the operating system of an instance. Every virtual server will have at least one block storage volume attached (referred to as the “root” volume) containing the operating system.
Block Storage volumes also back Persistent Volumes in our Managed Kubernetes services, so some of the concepts here will apply to those as well.
When creating a block storage volume you have the choice of creating an empty volume, or you can use a source image populate your new volume with some default content that you want to be present when attached to an instance. Details on how to create volumes from different sources are under this section of the documentation.
Block storage volumes can (with some exceptions) be detached or copied. Snapshots and backups can be made of them, and they can be attached to different servers as needed.
The block storage service implements techniques to reduce the impact of a physical failure, such as maintaining multiple copies of a block storage volume and regular checks to ensure these copies are consistent. However, you should always have backups of any block storage volumes, as failures can occur that affect data stored, and these features do not provide any means of recovery from deleted data inside the operating system. See Backups.
Block Storage volumes are tightly coupled to a specific location, and cannot be attached to servers in different locations. For storage that is distributed between regions, consider Object Storage instead.
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