What Is EVS?

Updated on 2025-02-27 GMT+08:00

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Overview

Elastic Volume Service (EVS) offers scalable block storage for cloud servers. EVS disks provide high reliability, high performance, and come with a variety of disk types. They can be used for distributed file systems, development and test environments, data warehouses, and high-performance computing (HPC) applications. Cloud servers that EVS supports include Elastic Cloud Servers (ECSs) and Bare Metal Servers (BMSs).

Just like the physical disks in local PC need to be installed before they can be used, EVS disks need to be attached to servers before they can be used. They cannot be used alone. You also need to partition and create file systems on them before they can be used for persistent data storage.

In this document, EVS disks are sometimes just referred to as "disks".

Figure 1 EVS architecture

EVS Advantages

EVS has the following advantages.

**Table 1** EVS advantages
Advantage	Description
Various disk types	EVS provides a variety of disk types for you to choose from. They can be used as data disks or system disks for cloud servers. You can select whichever disk type that has the specifications best suited to your budget and service requirements.
Elastic scalability	The EVS disk capacity ranges from 10 GiB to 32 TiB. You can start with 10 GiB, and if, later on, that no longer meets your needs, you can expand the disk capacity to up to 32 TiB in increments of 1 GiB, without interrupting your applications.
Elastic scalability	In addition to the disk capacity limit, there is an EVS capacity quota. The additional space you add cannot exceed the remaining quota. However, if this happens, you can apply for a higher quota.
High security and reliability	Data protection functions, such as backups, safeguard the disk data. If your data is ever damaged by a software exception or online attack, you can restore your data from backups.
High security and reliability	Data protection functions, such as snapshots, safeguard the disk data. If your data is ever damaged by a software exception or online attack, you can restore your data from snapshots.
Real-time monitoring	On Cloud Eye, you can monitor the disk health and operating status at any time.

Differences Among EVS, SFS, and OBS

There are three types of storage available for you to choose from: EVS, Scalable File Service (SFS), and Object Storage Service (OBS). Their differences are described in the following table.

**Table 2** Differences among EVS, SFS, and OBS
Service	Overall Introduction	Typical Application Scenarios	Storage Capacity
EVS	EVS provides scalable block storage that features high reliability, high performance, and a variety of specifications for servers.	Enterprise office applications Development and testing Enterprise applications, including SAP, Microsoft Exchange, and Microsoft SharePoint Distributed file systems Various databases, including MongoDB, Oracle, SQL Server, MySQL, and PostgreSQL	EVS disks start at 10 GiB and can be expanded as required in 1 GiB increments to up to 32 TiB.
SFS	SFS provides completely hosted shared file storage for cloud servers. Compatible with the Network File System (NFS) protocol, SFS is expandable to pebibyte and seamlessly handles data-intensive and bandwidth-intensive applications.	HPC scenarios, such as gene sequencing, animation rendering, and CAD/CAE File sharing Media processing Content management and web services Offline file backup	SFS storage capacity is available on demand and can be expanded to a maximum of 2 PiB.
OBS	OBS provides cloud storage for unstructured data, such as files, pictures, and videos. With multiple options for migration to the cloud, OBS provides low-cost, reliable storage access for massive data and supports online multimedia processing.	Enterprise backup and archive Big data analysis Enterprise cloud box Static website hosting Cloud-native applications	OBS has limitless storage capacity, and storage resources are available for linear and nearly infinite expansion.

Access Methods

EVS provides a web-based console and HTTPS-based APIs that you can use to access the EVS service.

APIs
Use APIs if you need to integrate EVS into a third-party system for secondary development. For details, see Elastic Volume Service API Reference.
Console
Use the console if you do not need to integrate EVS with a third-party system. Log in to the console and choose Elastic Volume Service from the service list.

Parent topic: Overview

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Next topic: Disk Types and Performance

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