Overview Azure SQL Database managed instance resource limits

This article provides an overview of the resource limits for Azure SQL Database managed instance, and provides information about how to request an increase to these limits.

Note

For differences in supported features and T-SQL statements see Feature differences and T-SQL statement support.

Instance-level resource limits

Managed instance has characteristics and resource limits that depend on the underlying infrastructure and architecture. Limits depend on hardware generation and service tier.

Hardware generation characteristics

Azure SQL Database managed instance can be deployed on two hardware generations: Gen4 and Gen5. Hardware generations have different characteristics, as described in the following table:

Gen4 Gen5
Hardware Intel E5-2673 v3 (Haswell) 2.4-GHz processors, attached SSD vCore = 1 PP (physical core) Intel E5-2673 v4 (Broadwell) 2.3-GHz processors, fast NVMe SSD, vCore=1 LP (hyper-thread)
Number of vCores 8, 16, 24 vCores 4, 8, 16, 24, 32, 40, 64, 80 vCores
Max memory (memory/core ratio) 7 GB per vCore
Add more vCores to get more memory.
5.1 GB per vCore
Add more vCores to get more memory.
Max In-Memory OLTP memory Instance limit: 3 GB per vCore
Database limits:
- 8-core: 8 GB per database
- 16-core: 20 GB per database
- 24-core: 36 GB per database
Instance limit: 2.5 GB per vCore
Database limits:
- 8-core: 13 GB per database
- 16-core: 32 GB per database
Max instance reserved storage General Purpose:8 TB
Business Critical: 1TB
General Purpose: 8 TB
Business Critical 1 TB, 2 TB, or 4 TB depending on the number of cores

Important

  • Gen4 hardware is being phased out. It is recommended to deploy new managed instances on Gen5 hardware.
  • Gen4 hardware at this time is available in the following regions: North Europe, West Europe, East US, South Central US, North Central US, West US 2, Central US, Canada Central, South India, Southeast Asia and Korea Central.

Service tier characteristics

Managed instance has two service tiers: General Purpose and Business Critical. These tiers provide different capabilities, as described in the table below:

Feature General Purpose Business Critical
Number of vCores* Gen4: 8, 16, 24
Gen5: 4, 8, 16, 24, 32, 40, 64, 80
Gen4: 8, 16, 24
Gen5: 4, 8, 16, 24, 32, 40, 64, 80
Max memory Gen4: 56 GB - 168 GB (7GB/vCore)
Gen5: 40.8 GB - 408 GB (5.1GB/vCore)
Add more vCores to get more memory.
Gen4: 56 GB - 168 GB (7GB/vCore)
Gen5: 40.8 GB - 408 GB (5.1GB/vCore)
Add more vCores to get more memory.
Max instance reserved storage size - 2 TB for 4 vCores (Gen5 only)
- 8 TB for other sizes
Gen4: 1 TB
Gen5:
- 1 TB for 4, 8, 16 vCores
- 2 TB for 24 vCores
- 4 TB for 32, 40, 64, 80 vCores
Max database size 8 TB 4 TB
Max number of databases per instance 100 100
Max number of database files per instance Up to 280 32,767 files per database
Max file size 8 TB 4 TB
Max log file size 2 TB 2 TB
Data/Log IOPS (approximate) 500 - 7,500 per file
*Increase file size to get more IOPS
5.5 K - 110 K (1375/vCore)
Add more vCores to get better IO performance.
Log write throughput limit 3 MB/s per vCore
Max 22 MB/s per instance
4 MB/s per vCore
Max 48 MB/s per instance
Data throughput (approximate) 100 - 250 MB/s per file
*Increase the file size to get better IO performance
N/A
Storage IO latency (approximate) 5-10 ms 1-2 ms
Max tempDB size 192 - 1,920 GB (24 GB per vCore)
Add more vCores to get more TempDB space.
Limited by the max instance storage size. TempDB log file size is currently limited to 24GB/vCore.
In-memory OLTP Not supported Available
Max sessions 30000 30000
Read-only replicas 0 1 (included in price)

Note

  • Both data and log file size in the user and system databases are included in the instance storage size that is compared with the Max storage size limit. Use sys.master_files system view to determine the total used space by databases. Error logs are not persisted and not included in the size. Backups are not included in storage size.
  • Throughput and IOPS also depend on the page size that is not explicitly limited by managed instance. You can create another readable replica in different Azure region using Auto-failover groups.

Supported regions

Managed instances can be created only in supported regions. To create a managed instance in a region that is currently not supported, you can send a support request via the Azure portal.

Supported subscription types

Managed instance currently supports deployment only on the following types of subscriptions:

Regional resource limitations

Supported subscription types can contain a limited number of resources per region. Managed instance has two default limits per Azure region depending on a type of subscription type:

  • Subnet limit: The maximum number of subnets where managed instances are deployed in a single region.
  • vCore limit: The maximum number of vCores that can be deployed across all instances in a single region.

Note

These limits are default settings and not technical limitations. The limits can be increased on-demand by creating a special support request in the Azure portal if you need more managed instances in the current region. As an alternative, you can create new managed instances in another Azure region without sending support requests.

The following table shows the default regional limits for supported subscription types (default limits can be extended using support request described below):

Subscription type Max number of managed instance subnets Max number of vCore units*
Pay-as-you-go 3 320
CSP 8 (15 in some regions**) 960 (1440 in some regions**)
Pay-as-you-go Dev/Test 3 320
Enterprise Dev/Test 3 320
EA 8 (15 in some regions**) 960 (1440 in some regions**)
Visual Studio Enterprise 2 64
Visual Studio Professional and MSDN Platforms 2 32

* In planning deployments, please take into consideration that Business Critical (BC) service tier requires four (4) times more vCore capacity than General Purpose (GP) service tier. For example: 1 GP vCore = 1 vCore unit and 1 BC vCore = 4 vCore units. To simplify your consumption analysis against the default limits, summarize the vCore units across all subnets in the region where managed instances are deployed and compare the results with the instance unit limits for your subscription type. Max number of vCore units limit applies to each subscription in a region. There is no limit per individual subnets except that the sum of all vCores deployed across multiple subnets must be lower or equal to max number of vCore units.

** Larger subnet and vCore limits are available in the following regions: Australia East, East US, East US 2, North Europe, South Central US, Southeast Asia, UK South, West Europe, West US 2.

Obtaining a larger quota for SQL managed instance

If you need more managed instances in your current regions, send a support request to extend the quota using the Azure portal. To initiate the process of obtaining a larger quota:

  1. Open Help + support, and click New support request.

    Help and Support

  2. On the Basics tab for the new support request:

    • For Issue type, select Service and subscription limits (quotas).

    • For Subscription, select your subscription.

    • For Quota type, select SQL Database Managed Instance.

    • For Support plan, select your support plan.

      Issue type quota

  3. Click Next.

  4. On the Problem tab for the new support request:

    • For Severity, select the severity level of the problem.

    • For Details, provide additional information about your issue, including error messages.

    • For File upload, attach a file with more information (up to 4 MB).

      Problem details

      Important

      A valid request should include:

      • Region in which subscription limit needs to be increased.
      • Required number of vCores, per service tier in existing subnets after the quota increase (if any of the existing subnets needs to be expanded.
      • Required number of new subnets and total number of vCores per service tier within the new subnets (if you need to deploy managed instances in new subnets).
  5. Click Next.

  6. On the Contact Information tab for the new support request, enter preferred contact method (email or phone) and the contact details.

  7. Click Create.

Next steps