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Community Blog What is Elastic Block Storage

What is Elastic Block Storage

This article explains what Elastic Block Storage is and how Elastic Block Storage works.

What is Elastic Block Storage

Elastic Block Storage is a high-performance, low-latency block storage service for Alibaba Cloud ECS. It supports random read and write operations. An Elastic Block Storage device is similar to a physical disk. You can format an Elastic Block Storage device and create a file system on it to meet the data storage requirements of your business.

Elastic Block Storage devices

Cloud disk

Cloud disks are block-level storage devices provided by Alibaba Cloud for ECS instances. Cloud disks use a triplicate distributed mechanism and feature low latency, high performance, durability, and high reliability. Disks can be created, resized, and released at any time.

Local disk

Local disks are physical disks attached to physical machines that host ECS instances. Local disks provide local storage access capabilities for ECS instances. They are designed for business scenarios that require high storage I/O performance, a large amount of storage, and high cost-effective performance. Local disks feature low latency, high random IOPS and throughput, and excellent cost-effective performance.

The Data Security of Elastic Block Storage

Data reliability during read and write operations

Three copies of your business data are stored in the Elastic Block Storage cluster in the same zone to ensure 99.9999999% data reliability during read and write operations.

Proactive backup

You can create snapshots at regular intervals to enhance your data security. Snapshots are a backup service provided by Alibaba Cloud. They provide data backup capabilities for cloud disks to ensure that information such as logs and customer transactions are backed up.

Data erasure mechanism

When you delete a piece of data from cloud disks and Share Block Storage devices, it is completely erased from the distributed Block Storage system and can no longer be accessed by other users in any way. The following mechanisms are used to ensure that all data is erased:

  • The storage system performs sequential writes to append data to an existing file at the underlying layer of a cloud disk. This mechanism makes full use of the high-bandwidth and low-latency features of sequential write to a physical disk. Based on the features of appending data to an existing file, if you delete the logical space of a cloud disk, this operation is recorded as metadata. The storage system returns only zero for all requests of reading data from the logical space. Similarly, when you overwrite the data in the logical space of a cloud disk, the storage system does not directly overwrite the data in the logical space, but modifies the mapping between the logical space and the physical space. This ensures that data that has been overwritten can no longer be read. Data fragments that result from delete or overwrite operations are forcibly and permanently deleted from the underlying physical disks.
  • When a Block Storage device (cloud disk) is released, the storage system destroys the metadata of the device immediately to ensure that the data can no longer be accessed. At the same time, the physical storage space corresponding to the disk is recycled. The physical space must be cleared before it is re-assigned to store data. Before data is written to a new disk, the system returns only zero for all read requests.

Data encryption

We recommend that you encrypt the storage devices that you use if your applications are data-sensitive. Cloud disks and their snapshots are encrypted with keys based on the industry-standard AES-256 algorithm. Data is automatically encrypted when it is transmitted from ECS instances to cloud disks and automatically decrypted when the data is read.

Elastic Block Storage vs OSS vs Apsara File Storage NAS

  • Elastic Block Storage

A high-performance and low-latency block-level storage device provided by Alibaba Cloud for ECS instances. It supports random read and write operations, and can be attached to ECS instances as a system disk or data disk. You can partition and format a Block Storage device and create file systems on it in the same way as you do with a physical disk. Block Storage can meet the data storage requirements of most business scenarios.

  • OSS Object Storage Service

A huge storage space designed to store unstructured data on the Internet, such as images, audios, and videos. You can access the data stored in OSS anytime and anywhere by calling API operations. OSS is applicable to the business scenarios such as website construction, separation of dynamic and static resources, and acceleration of domain name access through CDN.

  • Apsara File Storage NAS

A storage space designed for storing a large amount of unstructured data that can be accessed based on standard file access protocols, such as the Network File System (NFS) protocol for Linux, and the Server Message Block (SMB, also called Common Internet File System (CIFS)) protocol for Windows. You can set permissions to allow different clients to access the same file at the same time. Apsara File Storage NAS is applicable to the business scenarios such as file sharing across departments in an enterprise, non-linear editing in radio and television industries, high-performance computing, and containerization.

Related Product

Object Storage Service (OSS)

Alibaba Cloud Object Storage Service (OSS) is an encrypted, secure, cost-effective, and easy-to-use object storage service that enables you to store, back up, and archive large amounts of data in the cloud, with a guaranteed durability of 99.9999999999%(12 9’s). RESTful APIs allow storage and access to OSS anywhere on the Internet. You can elastically scale the capacity and processing capability and choose from a variety of storage types to optimize the storage cost.

Elastic Block Storage

Elastic Block Storage is a block-level data storage service attached to Elastic Compute Service (ECS) instances and features low latency, persistence, and high reliability. Block Storage enables automatic replication within the same zone to avoid data loss caused by hardware failures and guarantee the stability and continuity of your workloads. You can manage Block Storage as you manage disks. For example, you can partition Block Storage devices that are attached to ECS instances and create file systems for Block Storage devices. You can also use Block Storage devices to achieve data persistence.

Related Blog

Block Storage Optimization and Comparison

In this article, we discuss optimizing the Alibaba Cloud Block Storage Service. We will also compare the storage solutions from Alibaba Cloud and give you a detailed overview to select the solution best suited for you.

What is Object Storage? Object vs File vs Block

In this article, we'll show how to do some basic OSS operations into a spring-boot application using an SDK interface provided by Alibaba Cloud wrapped on top of a spring dependency.

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