Block Storage provides high-performance, low-latency storage for Elastic Compute Service (ECS). It includes cloud disks, local disks, and elastic ephemeral disks, all of which you can use just like physical hard drives.
Cloud disks
Cloud disks are block-level data storage devices that use a distributed triplicate mechanism to achieve 99.9999999% (nine 9's) data durability.
By usage
Category
Description
System disks
Boot disks for ECS instances (created with instances, shared lifecycle).
Storage for system-related data, such as operating systems and program files.
Data disks
Storage for user data, logs, and applications (created independently or with instances)
By performance tier
NoteBecause Block storage performance varies by disk type, choose a disk that meets your workload and application requirements.
For information about billing of different cloud disks, see Billing of cloud disks.
ESSD-series disks
Category
Feature
Use cases
Billing
High IOPS.
Low latency.
Latency-sensitive applications or I/O-intensive business scenarios, such as:
Large-scale online transaction processing (OLTP) databases
NoSQL databases
Elasticsearch distributed logs
Capacity fees.
Decouple capacity from performance.
Option to enable the provisioned performance.
Option to enable the burst performance.
Performance scaling without capacity expansion.
Fluctuating workloads requiring burst capabilities.
All scenarios for which ESSDs are suitable.
Capacity fees.
Pay-as-you-go provisioned performance fees if it is enabled.
Pay-as-you-go burst performance fees if it is enabled.
High IOPS.
Zone-redundant storage.
Multi-zone disaster recovery for databases.
Cross-zone container deployment.
Self-managed or cloud-based Software as a Service (SaaS) services.
All scenarios for which ESSDs are suitable.
Capacity fees.
ESSD Entry disks
NoteESSD Entry disks can be attached to only instances of universal instance families and e economy instance families.
High IOPS.
Low latency.
Development and testing business
Usage as system disks.
Capacity fees.
Previous generation disks
Standard SSDs, ultra disks, and basic disks are cloud disks of the previous generation. They are unavailable for purchase in specific regions and zones. We recommend that you use ESSDs at performance level 0 (PL0 ESSDs) or ESSD Entry disks instead of ultra disks and basic disks, and use ESSD AutoPL disks instead of standard SSDs.
Category
Feature
Use cases
Billing
Standard SSDs
High random read/write performance.
High reliability.
I/O-intensive applications
Small and medium-sized relational databases and NoSQL databases
Capacity fees.
Ultra disks
High cost efficiency.
High reliability.
Development and testing business
Usage as system disks.
Capacity fees.
Basic disks
High cost efficiency.
Low-cost development and testing business that does not require high storage performance
Capacity fees.
Local disks
Local disks provide local storage for ECS instances and reside on the physical machines that host the instances. Local disks are suitable for scenarios that require high storage I/O performance, mass storage, and high cost efficiency. Alibaba Cloud provides two categories of local disks:
Category | Supported instance family | Scenario |
Local non-volatile memory express (NVMe) SSD | The following instance families use local NVMe SSDs:
| Instance families equipped with local NVMe SSDs are suitable for the following scenarios:
|
Local SATA HDD | The d3s, d2c, d2s, d1ne, and d1 big data instance families use local SATA HDDs. | Local SATA HDDs are the preferred storage media for industries such as Internet and finance that have high requirements for big data computing, storage, and analytics. These disks are suited for mass storage and offline computing scenarios and can meet the high requirements of distributed computing services such as Hadoop in terms of storage performance, storage capacity, and internal network bandwidth. |
For information about the performance of instance families with local SSDs and big data instance families, see Overview of instance families.
Elastic ephemeral disks
An elastic ephemeral disk is a block storage device that can be created alongside an ECS instance or separately created, with user-defined capacity for temporary data storage. It features high performance and cost-effectiveness.
Data security
The following features, except for the data erasure mechanisms, are unique to cloud disks and elastic ephemeral disks.
Distributed triplicate mechanism
Automatically replicates data across three physical nodes
Ensures 99.9999999% data durability during read/write operations.
Cloud disks only.
For more information, see Triplicate storage.
Proactive backup
Create snapshots for disks on a regular basis to enhance data security.
Use automatic snapshot policies for hands-free backups.
Data erasure mechanisms
Instant Blocking:
Deleted areas show zeros immediately.
Overwritten data becomes unreadable by updating location records.
Physical Removal:
Leftover data pieces are permanently wiped from disks.
Uses secure methods to prevent recovery.
Full Reset:
When you delete a disk:
All access records are destroyed.
Disk space is thoroughly cleared.
New users get a "blank" disk showing only zeros.
Data encryption
For sensitive data protection:
Auto-Encryption:
Encrypts data during transfer (ECS to disk).
Decrypts automatically when accessed.
AES-256 Security:
Protects both cloud disks and snapshots.
Meets banking-grade security standards.
For more information, see Encrypt cloud disks.
References
For information about the limits and quotas of Block Storage, see the Block storage section in the "Limits" topic.
For information about the common operations that you can perform on a cloud disk, see Guide to creating and using disks.
In addition to Block Storage, Alibaba Cloud provides other storage services, such as Object Storage Service (OSS) and File Storage NAS (NAS), to meet your business requirements in different scenarios. For more information, see Comparison of NAS, OSS, and EBS.