Block Storage is a high-performance, low-latency block-level storage service provided by Alibaba Cloud for ECS instances. You can format and create file systems on Block Storage devices, similar to physical hard drives, to meet the data storage requirements of most general business scenarios.
Use cases
Alibaba Cloud offers a variety of Block Storage devices for your ECS instances, including cloud disks based on a distributed storage architecture and local disks on the physical machines hosting the instances. These include:
A cloud disk is a block-level storage device provided by Alibaba Cloud for ECS instances. It uses a multi-replica distributed mechanism and offers low latency, high performance, high durability, and high reliability. You can create, resize, and release cloud disks at any time.
A local disk is a storage device on the physical machine hosting an ECS instance, providing the instance with local storage access. Local disks are ideal for scenarios that require high I/O performance and cost-effective bulk storage.
Performance
The key performance metrics for Block Storage devices include IOPS, throughput, and latency. Some Block Storage devices also have capacity requirements. For example, ESSD cloud disks of different performance levels have different capacity ranges. For detailed performance metrics, see Block storage performance.
Data durability and service availability
Within a single zone, your data is replicated and distributed across a Block Storage cluster, ensuring data stability during read and write operations. This provides 99.9999999% (nine 9s) data durability for your ECS instances.
To improve reliability, create regular snapshots to back up your cloud disks. This ensures that information, such as logs and customer transactions, can be restored from a backup. For more information, see Snapshot overview.
Scalability and elasticity
You can quickly partition or release a cloud disk and adjust its storage capacity in real time based on your business needs. As your business and application data grow, you can expand the storage capacity of a single instance by extending its cloud disks in several ways:
Resize an existing cloud disk, and then extend its partitions or create new ones.
Create a new cloud disk, attach it to an instance as a data disk, and then partition and format it.
Replace the system disk with a larger one.
Security
You can use RAM to grant other users permissions to access your cloud disks.
For data-sensitive applications, we recommend that you encrypt your storage devices. ECS cloud disk encryption uses the industry-standard AES-256 algorithm to encrypt cloud disks and their snapshots with a key. The system automatically encrypts data transferred from an ECS instance to a cloud disk and decrypts it when read. For more information, see Encrypted cloud disks.
Interfaces
The Block Storage API supports HTTP and HTTPS requests using the GET and POST methods. If you are familiar with network protocols and at least one programming language, we recommend using the API to manage your Block Storage resources. You can call Block Storage API operations by using Alibaba Cloud ECS SDKs, Alibaba Cloud CLI, or Alibaba Cloud API Explorer. These tools allow you to create, delete, query, attach, detach, and resize cloud disks. You can also use them to create, delete, and query cloud disk snapshots stored in OSS.
If you prefer a graphical web interface, you can use the ECS console to perform all the operations supported by the Block Storage API.
Billing
Like other Alibaba Cloud services, Block Storage offers two billing methods: pay-as-you-go and subscription. The pay-as-you-go method allows you to provision and release resources on demand without large upfront investments, potentially reducing costs by 30% to 80% compared to traditional hosting. The pre-paid subscription method can further lower your costs.
The supported billing methods vary depending on how a cloud disk is created:
A cloud disk created with an ECS instance uses the same billing method as the instance.
Subscription cloud disks created for an existing subscription ECS instance use the subscription billing method.
Cloud disks created on the Cloud Disks page support only the pay-as-you-go billing method.
Cloud disks created from a snapshot support only the pay-as-you-go billing method.
You can change the billing method of a cloud disk to flexibly manage your resources. For more information, see Convert the billing method of a cloud disk. You can use Storage Capacity Units (SCUs) to cover charges for certain types of pay-as-you-go cloud disks. For more information, see What is an SCU?.