A regional Enterprise SSD (ESSD) is a new type of ESSD. Data written to a regional ESSD is automatically stored across multiple zones that are physically isolated from each other in terms of data centers, racks, and power supplies. If a physical failure occurs in one zone, the disk continues to provide read and write services to ensure business continuity. This topic describes the specifications, billing, limits, and common operations for regional ESSDs.
Introduction to cloud disks
Advantages
A regional ESSD offers the following advantages over other disk products:
You do not need to understand the complex data replication logic of traditional on-premises storage. A regional ESSD relies entirely on physical replication and supports synchronous writes to multiple zones to achieve a recovery point objective (RPO) of 0.
You can achieve better business continuity with regional ESSDs without purchasing additional ECS instances, bandwidth, or compute resources for application-layer disaster recovery.
The product features are consistent with and retain the same enterprise-grade characteristics as standard ESSDs.
Data on a regional ESSD must be synchronously written to multiple zones. This results in higher average latency of random writes compared with a PL1 ESSD. Therefore, a regional ESSD is ideal if your business cannot tolerate data loss caused by a zone failure and is not sensitive to the average latency of random writes.
Scenarios
Multi-zone disaster recovery for databases
Traditional database deployment solutions use primary/secondary replication to achieve high availability and disaster recovery across zones. This solution has issues such as replication delays and data inconsistency between the primary and secondary databases. With a regional ESSD-based deployment, you can choose the most cost-effective deployment mode. You only need to deploy a compute node in Zone A and attach a regional ESSD. You do not need to deploy a compute node in Zone B or configure primary/secondary replication. The physical replication of the regional ESSD implements data redundancy across zones. In the event of a failure, you only need to start a compute node in Zone B to provide services. This reduces storage costs by 25% and compute costs by 50%.
Cross-zone container deployment
The elasticity and disaster recovery of stateful applications across zones remain a major challenge for container deployment. With a regional ESSD-based deployment, you can upgrade a stateful application from a single-zone application to an application with zone-level disaster recovery capabilities at no transformation cost. If a compute node or a zone fails, or if resources in a single zone are insufficient, you can migrate the container to another zone without complex data synchronization or data validation.
Self-managed or cloud-based Software as a Service (SaaS) deployment
When you build or deploy a SaaS service, you need to deploy two sets of ECS clusters in two zones to deliver the corresponding services. Regional ESSDs provide low-cost cross-zone capabilities.
Billing
Regional ESSDs are billed based on capacity. Both pay-as-you-go and subscription billing methods are supported. For more information about billing rules, see Elastic Block Storage billing.
Limits
Region limitations
Regional ESSDs are available only in the following regions: China (Hangzhou), China (Shanghai), China (Beijing), China (Zhangjiakou), China (Shenzhen), China (Hong Kong), Singapore, China (Ulanqab), Malaysia (Kuala Lumpur), and Indonesia (Jakarta).
Instance type limitations
For more information about the instance families that support regional ESSDs, see Instance families.
Feature limitations
Feature category | Feature | Supported by regional ESSDs |
Basic cloud disk features | Create, view, modify, and release a disk | Yes |
Data encryption | Encrypt | Yes |
Attach a Shared Cloud Disk | Multi-attach | Yes |
Asynchronous disk replication | Asynchronous replication |
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Data protection | Create snapshots/Use snapshot instant access | Yes |
Automatic snapshot policies | Yes | |
Create a disk from a snapshot | Yes | |
Snapshot-consistent groups | Yes Regional ESSDs can be added to a snapshot-consistent group only with other regional ESSDs. | |
Disk operations | Initialize a disk | Yes |
Resize a disk | Yes | |
Roll back a disk from a snapshot | Yes | |
Use as a system disk | No Regional ESSDs can be used only as data disks. | |
Attach a disk | Yes | |
Cloud Disk billing | Change the billing method of a disk | Yes |
Cloud Disk Specifications | Change disk category | Yes |
Performance elasticity | Provisioned performance | No |
Burst performance | No |
Cloud Disk Performance
The following table describes the specifications of regional ESSDs.
Performance Tier | Description |
Capacity range (GiB) | 10 to 65,536 |
Maximum IOPS per disk | 50,000 |
Maximum I/O size (KiB) | 16 |
Maximum throughput per disk (MB/s) | 350 |
Average latency of random writes per connection (ms) | Millisecond-level¹ |
IOPS performance formula per disk (baseline performance²) | min{1,800 + 50 × Capacity, 50,000} |
Throughput performance formula per disk (baseline performance, MB/s) | min{120 + 0.5 × Capacity, 350} |
①Latency varies across different regions and zones. You can test the average write latency of a zone-redundant disk as described in Test storage performance.
² Baseline performance: The maximum IOPS and throughput that a disk provides after it is created. The baseline performance increases linearly with the disk capacity. The maximum baseline performance varies by disk category.
Use a regional ESSD
Create a regional ESSD
Create a disk with an instance
Go to the ECS instance buy page.
Click the Custom Launch tab.
Configure parameters such as the billing method, region, instance type, and image as needed. When you create a regional ESSD, note the following parameters:
Select a region that supports regional ESSDs.
In the Storage section, set the data disk category to Regional ESSD and configure the disk size.
For more information about other parameters, see Create an instance on the custom launch tab.
Create separately
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Go to ECS console - Block Storage.
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In the top navigation bar, select the region and resource group of the resource that you want to manage.
Click Create Cloud Disk.
Configure the parameters.
Select a region that supports regional ESSDs.
Set the disk type to ESSD Zone-redundant and configure the disk size.
For more information about other parameters, see Create a data disk.
Attach the created regional ESSD to an ECS instance and initialize it before use.
For more information, see Attach a data disk.
Force-attach a regional ESSD
If a data center failure or an ECS instance exception prevents you from detaching a regional ESSD, you can force-attach it. This lets you attach the disk directly to another ECS instance in the same region without first detaching it, which accelerates service recovery.
The force-attach feature is available only for regional ESSDs. Other types of disks must be detached before they can be attached to another instance.
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Go to ECS console - Block Storage.
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In the top navigation bar, select the region and resource group of the resource that you want to manage.
Find the disk that you want to attach and click Attach in the Actions column.
Select the target instance and its release behavior. Select I Confirm To Move The Disk To Another Instance By Using The Force Attach Feature, and then follow the on-screen instructions to complete the attachment and initialization process.
If data in the original instance's memory cache has not been written to the disk before the force-attach operation, the data is lost. After the disk is force-attached, I/O requests from the original instance fail.
References
To convert a regional ESSD to another disk category or convert another disk category to a regional ESSD for performance tuning or capacity expansion, see Change the category of a disk.