Hyperscale service tier
Azure SQL Database is based on SQL Server Database Engine architecture that is adjusted for the cloud environment in order to ensure 99.99% availability even in the cases of infrastructure failures. There are three architectural models that are used in Azure SQL Database:
- General Purpose/Standard
- Business Critical/Premium
The Hyperscale service tier in Azure SQL Database is the newest service tier in the vCore-based purchasing model. This service tier is a highly scalable storage and compute performance tier that leverages the Azure architecture to scale out the storage and compute resources for an Azure SQL Database substantially beyond the limits available for the General Purpose and Business Critical service tiers.
For details on the General Purpose and Business Critical service tiers in the vCore-based purchasing model, see General Purpose and Business Critical service tiers. For a comparison of the vCore-based purchasing model with the DTU-based purchasing model, see Azure SQL Database purchasing models and resources.
What are the Hyperscale capabilities
The Hyperscale service tier in Azure SQL Database provides the following additional capabilities:
- Support for up to 100 TB of database size
- Nearly instantaneous database backups (based on file snapshots stored in Azure Blob storage) regardless of size with no IO impact on compute resources
- Fast database restores (based on file snapshots) in minutes rather than hours or days (not a size of data operation)
- Higher overall performance due to higher log throughput and faster transaction commit times regardless of data volumes
- Rapid scale out - you can provision one or more read-only nodes for offloading your read workload and for use as hot-standbys
- Rapid Scale up - you can, in constant time, scale up your compute resources to accommodate heavy workloads as and when needed, and then scale the compute resources back down when not needed.
The Hyperscale service tier removes many of the practical limits traditionally seen in cloud databases. Where most other databases are limited by the resources available in a single node, databases in the Hyperscale service tier have no such limits. With its flexible storage architecture, storage grows as needed. In fact, Hyperscale databases aren’t created with a defined max size. A Hyperscale database grows as needed - and you are billed only for the capacity you use. For read-intensive workloads, the Hyperscale service tier provides rapid scale-out by provisioning additional read replicas as needed for offloading read workloads.
Additionally, the time required to create database backups or to scale up or down is no longer tied to the volume of data in the database. Hyperscale databases can be backed up virtually instantaneously. You can also scale a database in the tens of terabytes up or down in minutes. This capability frees you from concerns about being boxed in by your initial configuration choices.
For more information about the compute sizes for the Hyperscale service tier, see Service tier characteristics.
Who should consider the Hyperscale service tier
The Hyperscale service tier is intended for most business workloads as it provides great flexibility and high performance with independently scalable compute and storage resources. With the ability to auto-scale storage up to 100 TB, it's a great choice for customers who:
- Have large databases on-premises and want to modernize their applications by moving to the cloud
- Are already in the cloud and are limited by the maximum database size restrictions of other service tiers (1-4 TB)
- Have smaller databases, but require fast vertical and horizontal compute scaling, high performance, instant backup, and fast database restore.
The Hyperscale service tier supports a broad range of SQL Server workloads, from pure OLTP to pure analytics, but it is primarily optimized for OLTP and hybrid transaction and analytical processing (HTAP) workloads.
Elastic pools do not support the Hyperscale service tier.
Hyperscale pricing model
Hyperscale service tier is only available in vCore model. To align with the new architecture, the pricing model is slightly different from General Purpose or Business Critical service tiers:
The Hyperscale compute unit price is per replica. The Azure Hybrid Benefit price is applied to read scale replicas automatically. We create a primary replica and one read-only replica per Hyperscale database by default. Users may adjust the total number of replicas including the primary from 1-5.
You don't need to specify the max data size when configuring a Hyperscale database. In the hyperscale tier, you are charged for storage for your database based on actual usage. Storage is automatically allocated between 10 GB and 100 TB, in increments that are dynamically adjusted between 10 GB and 40 GB.
For more information about Hyperscale pricing, see Azure SQL Database Pricing
Distributed functions architecture
Unlike traditional database engines that have centralized all of the data management functions in one location/process (even so called distributed databases in production today have multiple copies of a monolithic data engine), a Hyperscale database separates the query processing engine, where the semantics of various data engines diverge, from the components that provide long-term storage and durability for the data. In this way, the storage capacity can be smoothly scaled out as far as needed (initial target is 100 TB). Read-only replicas share the same storage components so no data copy is required to spin up a new readable replica.
The following diagram illustrates the different types of nodes in a Hyperscale database:
A Hyperscale database contains the following different types of components:
The compute node is where the relational engine lives, so all the language elements, query processing, and so on, occur. All user interactions with a Hyperscale database happen through these compute nodes. Compute nodes have SSD-based caches (labeled RBPEX - Resilient Buffer Pool Extension in the preceding diagram) to minimize the number of network round trips required to fetch a page of data. There is one primary compute node where all the read-write workloads and transactions are processed. There are one or more secondary compute nodes that act as hot standby nodes for failover purposes, as well as act as read-only compute nodes for offloading read workloads (if this functionality is desired).
Page servers are systems representing a scaled-out storage engine. Each page server is responsible for a subset of the pages in the database. Nominally, each page server controls between 128 GB and 1 TB of data. No data is shared on more than one page server (outside of replicas that are kept for redundancy and availability). The job of a page server is to serve database pages out to the compute nodes on demand, and to keep the pages updated as transactions update data. Page servers are kept up-to-date by playing log records from the log service. Page servers also maintain SSD-based caches to enhance performance. Long-term storage of data pages is kept in Azure Storage for additional reliability.
The log service accepts log records from the primary compute replica, persists them in a durable cache, and forwards the log records to the rest of compute replicas (so they can update their caches) as well as the relevant page server(s), so that the data can be updated there. In this way, all data changes from the primary compute replica are propagated through the log service to all the secondary compute replicas and page servers. Finally, the log records are pushed out to long-term storage in Azure Storage, which is a virtually infinite storage repository. This mechanism removes the need for frequent log truncation. The log service also has local cache to speed up access to log records.
Azure Storage contains all data files in a database. Page servers keep data files in Azure Storage up to date. This storage is used for backup purposes, as well as for replication between Azure regions. Backups are implemented using storage snapshots of data files. Restore operations using snapshots are fast regardless of data size. Data can be restored to any point in time within the backup retention period of the database.
Backup and restore
Backups are file-snapshot based and hence they are nearly instantaneous. Storage and compute separation enables pushing down the backup/restore operation to the storage layer to reduce the processing burden on the primary compute replica. As a result, database backup does not impact performance of the primary compute node; similarly, restores are done by reverting to file snapshots, and as such are not a size of data operation. Restore is a constant-time operation, and even multiple-terabyte databases can be restored in minutes instead of hours or days. Creation of new databases by restoring an existing backup also takes advantage of this feature: creating database copies for development or testing purposes, even of terabyte sized databases, is doable in minutes.
Scale and performance advantages
With the ability to rapidly spin up/down additional read-only compute nodes, the Hyperscale architecture allows significant read scale capabilities and can also free up the primary compute node for serving more write requests. Also, the compute nodes can be scaled up/down rapidly due to the shared-storage architecture of the Hyperscale architecture.
Create a HyperScale database
The following T-SQL command creates a Hyperscale database. You must specify both the edition and service objective in the
CREATE DATABASE statement. Refer to the resource limits for a list of valid service objectives.
-- Create a HyperScale Database CREATE DATABASE [HyperScaleDB1] (EDITION = 'HyperScale', SERVICE_OBJECTIVE = 'HS_Gen5_4'); GO
This will create a Hyperscale database on Gen5 hardware with 4 cores.
Migrate an existing Azure SQL Database to the Hyperscale service tier
You can move your existing Azure SQL databases to Hyperscale using the Azure portal, T-SQL, Powershell or CLI. At this time, this is a one-way migration. You can't move databases from Hyperscale to another service tier, other than by exporting and importing data. For proofs of concept (POCs), we recommend making a copy of your production databases, and migrating the copy to Hyperscale. Migrating an existing Azure SQL database to the Hyperscale tier is a size of data operation.
The following T-SQL command moves a database into the Hyperscale service tier. You must specify both the edition and service objective in the
ALTER DATABASE statement.
-- Alter a database to make it a HyperScale Database ALTER DATABASE [DB2] MODIFY (EDITION = 'HyperScale', SERVICE_OBJECTIVE = 'HS_Gen5_4'); GO
Connect to a read-scale replica of a Hyperscale database
In HyperScale databases, the
ApplicationIntent argument in the connection string provided by the client dictates whether the connection is routed to the write replica or to a read-only secondary replica. If the
ApplicationIntent set to
READONLY and the database does not have a secondary replica, connection will be routed to the primary replica and defaults to
-- Connection string with application intent Server=tcp:<myserver>.database.windows.net;Database=<mydatabase>;ApplicationIntent=ReadOnly;User ID=<myLogin>;Password=<myPassword>;Trusted_Connection=False; Encrypt=True;
Hyperscale secondary replicas are all identical, using the same Service Level Objective as the primary replica. If more than one secondary replica is present, the workload is distributed across all available secondaries. Each secondary replica is updated independently, thus different replicas could have different data latency relative to the primary replica.
Database High Availability in Hyperscale
As in all other service tiers, Hyperscale guarantees data durability for committed transactions regardless of compute replica availability. The extent of downtime due to the primary replica becoming unavailable depends on the type of failover (planned vs. unplanned), and on the presence of at least one secondary replica. In a planned failover (i.e. a maintenance event), the system either creates the new primary replica before initiating a failover, or uses an existing secondary replica as the failover target. In an unplanned failover (i.e. a hardware failure on the primary replica), the system uses a secondary replica as a failover target if one exists, or creates a new primary replica from the pool of available compute capacity. In the latter case, downtime duration is longer due to extra steps required to create the new primary replica.
For Hyperscale SLA, see SLA for Azure SQL Database.
Disaster Recovery for Hyperscale Databases
Restoring a Hyperscale database to a different geography
If you need to restore an Azure SQL Database Hyperscale DB to a region other than the one it is currently hosted in, as part of a disaster recovery operation or drill, relocation, or any other reason, the primary method is to do a geo-restore of the database. This involves exactly the same steps as what you would use to restore any other AZURE SQL DB to a different region:
- Create a SQL Database server in the target region if you do not already have an appropriate server there. This server should be owned by the same subscription as the original (source) server.
- Follow the instructions in the geo-restore topic of the page on restoring Azure SQL Databases from automatic backups.
Because the source and target are in separate regions, the database cannot share snapshot storage with the source database as in non-geo restores, which complete extremely quickly. In the case of a geo-restore of a Hyperscale database, it will be a size-of-data operation, even if the target is in the paired region of the geo-replicated storage. That means that doing a geo-restore will take time proportional to the size of the database being restored. If the target is in the paired region, the copy will be within a datacenter, which will be significantly faster than a long distance copy over the internet, but it will still copy all of the bits.
The Azure SQL Database Hyperscale tier is currently available in the following regions:
- Australia East
- Australia Southeast
- Brazil South
- Canada Central
- Central US
- China East 2
- China North 2
- East Asia
- East US
- East Us 2
- France Central
- Japan East
- Japan West
- Korea Central
- Korea South
- North Central US
- North Europe
- South Africa North
- South Central US
- Southeast Asia
- UK South
- UK West
- West Europe
- West US
- West US 2
If you want to create Hyperscale database in a region that is not listed as supported, you can send an onboarding request via Azure portal. We are working to expand the list of supported regions so please check back for latest region list.
To request the ability to create Hyperscale databases in regions not listed:
Navigate to Azure Help and Support Blade
Click on New support request
For Issue Type, select Service and subscription limits (quotas)
Choose the subscription you would use to create the database(s)
For Quota Type, select SQL database
Click Next: Solutions
Click Provide Details
Choose SQL Database quota type: Other quota request
Fill in the following template:
In the template, provide the following information
Request to create Azure Hyperscale SQL Database in a new region
Region: [Fill in your requested region]
Compute SKU/total cores including readable replicas
Number of TB estimated
Choose Severity C
Choose the appropriate contact method and fill in details.
Click Save and Continue
These are the current limitations to the Hyperscale service tier as of GA. We are actively working to remove as many of these limitations as possible.
|The Manage Backups pane for a logical server does not show Hyperscale databases will be filtered from SQL server||Hyperscale has a separate method for managing backups, and as such the Long-Term Retention and Point in Time backup Retention settings do not apply / are invalidated. Accordingly, Hyperscale databases do not appear in the Manage Backup pane.|
|Point-in-time restore||Once a database is migrated into the Hyperscale service tier, restore to a point-in-time prior to the migration is not supported.|
|Restore of non-Hyperscale DB to Hypserscale and vice-versa||You cannot restore a Hyperscale database into a non-Hyperscale database, nor can you restore a non-Hyperscale database into a Hyperscale database.|
|If a database has one or more data files larger than 1 TB, migration fails||In some cases, it may be possible to work around this issue by shrinking the large files to be less than 1 TB. If migrating a database being used during the migration process, make sure that no file gets larger than 1 TB. Use the following query to determine the size of database files.
|Managed Instance||Azure SQL Database Managed Instance is not currently supported with Hyperscale databases.|
|Elastic Pools||Elastic Pools are not currently supported with SQL Database Hyperscale.|
|Migration to Hyperscale is currently a one-way operation||Once a database is migrated to Hyperscale, it cannot be migrated directly to a non-Hyperscale service tier. At present, the only way to migrate a database from Hyperscale to non-Hyperscale is to export/import using a BACPAC file or other data movement technologies (Bulk Copy, Azure Data Factory, Azure Databricks, SSIS, etc.)|
|Migration of databases with persistent in-memory objects||Hyperscale only supports non persistent In-Memory objects (table types, native SPs and functions). Persistent In-Memory tables and other objects must be dropped and recreated as non-In-Memory objects before migrating a database to the Hyperscale service tier.|
|Change Tracking||You cannot yet configure and use Change Tracking with Azure SQL Hyperscale databases.|
|Geo Replication||You cannot yet configure geo-replication for Azure SQL Database Hyperscale.|
|Database Copy||You cannot yet use Database Copy to create a new database in Azure SQL Hyperscale.|
|TDE/AKV Integration||Transparent Database Encryption using Azure Key Vault (commonly referred to as Bring-Your-Own-Key or BYOK) is not yet supported for Azure SQL Database Hyperscale, however TDE with Service Managed Keys is fully supported.|
|Intelligent Database Features||With the exception of the "Force Plan" option, all other Automatic tuning options are not yet supported on Hyperscale: options may appear to be enabled, but there won't be any recommendations or actions made.|
- For an FAQ on Hyperscale, see Frequently asked questions about Hyperscale.
- For information about service tiers, see Service tiers
- See Overview of resource limits on a logical server for information about limits at the server and subscription levels.
- For purchasing model limits for a single database, see Azure SQL Database vCore-based purchasing model limits for a single database.
- For a features and comparison list, see SQL common features.