EVS Basics and Disk Types

What Is EVS?

Elastic Volume Service (EVS) offers scalable block storage for cloud servers. With high reliability, high performance, and a variety of specifications, EVS disks can be used for distributed file systems, development and test environments, data warehouses, and high-performance computing (HPC) applications.

Similar to a physical disk in a PC, you must attach an EVS disk to a cloud server in the same AZ before you can use it. EVS disks are sometimes just referred to as disks.

Disk Types and Performance

EVS offers a variety of disk types. You can choose appropriate disk types based on your service requirements.

EVS allows you to change the disk type if it no longer meets your needs.

Basic Concepts

• IOPS

  Number of read/write operations performed by an EVS disk per second

• Throughput

  Amount of data read from and written into an EVS disk per second

• Shared EVS disk

  A shared EVS disk is a block storage device that supports concurrent reads/writes from multiple servers and can even be attached to multiple servers at the same time.

  Note that shared EVS disks must be used together with a distributed file system or clustered software.

• EVS snapshot

  An EVS snapshot is a complete copy or image of the disk data at a specific point in time, which can be used for data disaster recovery.

• EVS backup

  EVS backup protects disk data against viruses, accidental deletions, or software or hardware faults. You can use backups to restore data to any point when the data was backed up.