Regional Enterprise SSD (ESSD) is a new cloud disk category for Elastic Compute Service (ECS) instances. Data written to a Regional ESSD can be automatically stored in multiple zones within the same region. Regional ESSDs are physically isolated from data centers, racks, and power supplies. In the event of physical failures in a zone, the Regional ESSD allows for continuous reads and writes to ensure business continuity. This topic describes the specifications, billing, limits, and common operations of Regional ESSDs.
Regional ESSD
Advantages
Regional ESSDs have the following advantages over other categories of cloud disks:
You do not need to be familiar with the complex data replication logic of traditional offline storage. Regional ESSDs allow data to be replicated and synchronously written across multiple zones to achieve a recovery point objective (RPO) of 0.
During application-layer disaster recovery, you do not need to purchase additional ECS instances, bandwidth, or computing resources. You can use Regional ESSDs to achieve better business continuity.
Regional ESSDs inherit enterprise-level features that ESSDs support.
Data on Regional ESSDs needs to be synchronously written across multiple zones, which result in a higher average latency compared with ESSDs of performance level 1 (PL1 ESSDs). If your business requires zero data loss in the event of zone failures and can accommodate increased write latency, Regional ESSDs are a suitable option.
Scenarios
Multi-zone disaster recovery for databases
The traditional database deployment solution uses primary/secondary replication to ensure high availability and implement disaster recovery across zones. However, the solution has issues, such as primary/secondary replication latency and data inconsistency. Regional ESSDs provide you with a cost-effectiveness deployment pattern. You need to only deploy one compute node in one zone (Zone A) and attach a Regional ESSD to the compute node. You do not need to deploy additional compute nodes in another zone (Zone B) or configure primary/secondary replication. You can directly use the physical replication feature of Regional ESSDs to implement data redundancy across zones. If a failure occurs in Zone A, you need to only deploy a compute node in Zone B and attach the Regional ESSD to the compute node in Zone B to continue providing services. This reduces storage costs by 25% and computing costs by 50%.
Cross-zone container deployment
Cross-zone elasticity and disaster recovery for stateful applications remain major challenges in container deployment. Regional ESSDs provide stateful applications in individual zones with cross-zone disaster recovery capabilities at zero cost. If a compute node or a zone fails or the resources in a zone are insufficient, the containers can be migrated to another zone without the need for complex data synchronization or data verification.
Build self-managed Software as a Service (SaaS) services or deploy SaaS services in the cloud
When you build self-managed SaaS services or deploy SaaS services in the cloud, you must build two sets of ECS clusters in two zones to provide the corresponding services based on Regional ESSDs. Regional ESSDs provide low-cost cross-zone capabilities.
Billing
You are charged for the disk capacity of Regional ESSDs. You can use the pay-as-you-go or subscription billing method. For information about the billing rules of Regional ESSDs, see Block storage devices.
Limits
Region limits
Regional ESSDs are available only in the following regions: China (Hangzhou), China (Shanghai), China (Beijing), China (Zhangjiakou), China (Shenzhen), China (Hong Kong), and Singapore.
Instance type limits
For information about the instance families that support Regional ESSDs, see Overview of instance families.
Feature limits
Feature type | Feature | Supported by Regional ESSDs |
Basic features of cloud disks | Create, view, modify, and release disks. | Yes |
Cloud data encryption | Encrypt data stored on cloud disks. | Yes |
Cloud disk multi-attach | Attach a cloud disk to multiple ECS instances. | Yes |
Cloud disk async replication | Perform async replication. |
|
Data protection | Create snapshots and use the instant access feature. | Yes |
Create automatic snapshot policies. | Yes | |
Create cloud disks from snapshots. | Yes | |
Create snapshot-consistent groups. | No | |
Cloud disk operations | Initialize cloud disks. | Yes |
Resize cloud disks. | Yes | |
Roll back a cloud disk by using a snapshot. | Yes | |
Use a cloud disk as a system disk. | No Note Regional ESSDs can be used only as data disks. | |
Attach a cloud disk to an ECS instance. | Yes | |
Billing of cloud disks | Change the billing method of a cloud disk. | Yes |
Disk specifications | Change the category of a cloud disk. | No |
Performance elasticity | Configure performance provisions. | No |
Configure burst performance. | No |
Disk performance
The following table describes the specifications of Regional ESSDs.
Metric | Description |
Capacity range (GiB) | 10 to 65,536 |
Maximum IOPS per disk | 50,000 |
Maximum I/O size (KB) | 16 |
Maximum throughput per disk (MB/s) | 350 |
Average random write latency per connection (ms) | Several milliseconds① |
Formula for calculating the IOPS per disk (baseline performance) | min{1,800 + 50 × Capacity, 50,000} |
Formula for calculating the throughput performance per disk (baseline performance, in MB/s) | min{120 + 0.5 × Capacity, 350} |
①Latency varies based on regions and zones. You can perform the operations described in Test the performance of block storage devices to test the average write latency of Regional ESSDs.
Use Regional ESSDs
Create Regional ESSDs
Create a Regional ESSD when you create an ECS instance
Go to the instance buy page in the ECS console.
Click the Custom Launch tab.
Configure parameters, such as Billing Method, Region, Instance Type, and Image, based on your business requirements. When you create a Regional ESSD, take note of the following parameters:
Select a region in which Regional ESSDs are supported.
In the Storage section, set the data disk category to Regional ESSD and specify the size of the Regional ESSD.
For information about other parameters, see Create an instance on the Custom Launch tab.
Separately create a Regional ESSD
Go to ECS console - Block Storage.
In the top navigation bar, select the region and resource group of the resource that you want to manage.
Click Create Cloud Disk.
Configure parameters based on your business requirements.
Select a region in which Regional ESSDs are supported.
Set the disk category to Regional ESSD and specify the size of the Regional ESSD.
For information about other parameters, see Create an empty data disk.
Attach the created Regional ESSD to an ECS instance and initialize the Regional ESSD.
For more information, see Attach a data disk.
Force attach a Regional ESSD
If a data center-level or instance-level fault occurs, you may be unable to detach a Regional ESSD from an ECS instance. In this case, you can force attach the Regional ESSD to a different ECS instance that resides in the same region as the original ECS instance without the need to first detach the Regional ESSD from the original ECS instance. This accelerates service recovery.
The force attach operation applies only to Regional ESSDs. For other categories of cloud disks, you must detach the disks from the original ECS instance before you can attach the disks to a different ECS instance.
Go to ECS console - Block Storage.
In the top navigation bar, select the region and resource group of the resource that you want to manage.
Find the Regional ESSD that you want to manage and click Attach in the Actions column.
Select the ECS instance to which you want to attach the Regional ESSD and the release mode, select I confirm to move the disk to another instance by using the force attach feature, and then follow the on-screen instructions to attach and initialize the Regional ESSD.
If the original ECS instance has data not written to the Regional ESSD, such as data in memory, the instance rejects the I/O requests related to the Regional ESSD and returns failures for the requests after you force attach the Regional ESSD to a different ECS instance.