Resources limits for elastic pools using the DTU-based purchasing model

This article provides the detailed resource limits for Azure SQL Database elastic pools and pooled databases using the DTU-based purchasing model.

For DTU-based purchasing model resource limits for single databases, see DTU-based resource limits - single databases. For vCore-based resource limits, see vCore-based resource limits - single databases and vCore-based resource limits - elastic pools.

Important

Under some circumstances, you may need to shrink a database to reclaim unused space. For more information, see Manage file space in Azure SQL Database.

Elastic pool: Storage sizes and compute sizes

For SQL Database elastic pools, the following tables show the resources available at each service tier and compute size. You can set the service tier, compute size, and storage amount using the Azure portal, PowerShell, the Azure CLI, or the REST API.

Note

The resource limits of individual databases in elastic pools are generally the same as for single databases outside of pools based on DTUs and the service tier. For example, the max concurrent workers for an S2 database is 120 workers. So, the max concurrent workers for a database in a Standard pool is also 120 workers if the max DTU per database in the pool is 50 DTUs (which is equivalent to S2).

Basic elastic pool limits

eDTUs per pool 50 100 200 300 400 800 1200 1600
Included storage per pool (GB) 5 10 20 29 39 78 117 156
Max storage choices per pool (GB) 5 10 20 29 39 78 117 156
Max In-Memory OLTP storage per pool (GB) N/A N/A N/A N/A N/A N/A N/A N/A
Max number DBs per pool 100 200 500 500 500 500 500 500
Max concurrent workers (requests) per pool 100 200 400 600 800 1600 2400 3200
Max concurrent sessions per pool 30000 30000 30000 30000 30000 30000 30000 30000
Min eDTUs choices per database 0, 5 0, 5 0, 5 0, 5 0, 5 0, 5 0, 5 0, 5
Max eDTUs choices per database 5 5 5 5 5 5 5 5
Max storage per database (GB) 2 2 2 2 2 2 2 2

Standard elastic pool limits

eDTUs per pool 50 100 200 300 400 800
Included storage per pool (GB) 50 100 200 300 400 800
Max storage choices per pool (GB) 50, 250, 500 100, 250, 500, 750 200, 250, 500, 750, 1024 300, 500, 750, 1024, 1280 400, 500, 750, 1024, 1280, 1536 800, 1024, 1280, 1536, 1792, 2048
Max In-Memory OLTP storage per pool (GB) N/A N/A N/A N/A N/A N/A
Max number DBs per pool 100 200 500 500 500 500
Max concurrent workers (requests) per pool 100 200 400 600 800 1600
Max concurrent sessions per pool 30000 30000 30000 30000 30000 30000
Min eDTUs choices per database 0, 10, 20, 50 0, 10, 20, 50, 100 0, 10, 20, 50, 100, 200 0, 10, 20, 50, 100, 200, 300 0, 10, 20, 50, 100, 200, 300, 400 0, 10, 20, 50, 100, 200, 300, 400, 800
Max eDTUs choices per database 10, 20, 50 10, 20, 50, 100 10, 20, 50, 100, 200 10, 20, 50, 100, 200, 300 10, 20, 50, 100, 200, 300, 400 10, 20, 50, 100, 200, 300, 400, 800
Max storage per database (GB) 500 750 1024 1024 1024 1024

Standard elastic pool limits (continued)

eDTUs per pool 1200 1600 2000 2500 3000
Included storage per pool (GB) 1200 1600 2000 2500 3000
Max storage choices per pool (GB) 1200, 1280, 1536, 1792, 2048, 2304, 2560 1600, 1792, 2048, 2304, 2560, 2816, 3072 2000, 2048, 2304, 2560, 2816, 3072, 3328, 3584 2500, 2560, 2816, 3072, 3328, 3584, 3840, 4096 3000, 3072, 3328, 3584, 3840, 4096
Max In-Memory OLTP storage per pool (GB) N/A N/A N/A N/A N/A
Max number DBs per pool 500 500 500 500 500
Max concurrent workers (requests) per pool 2400 3200 4000 5000 6000
Max concurrent sessions per pool 30000 30000 30000 30000 30000
Min eDTUs choices per database 0, 10, 20, 50, 100, 200, 300, 400, 800, 1200 0, 10, 20, 50, 100, 200, 300, 400, 800, 1200, 1600 0, 10, 20, 50, 100, 200, 300, 400, 800, 1200, 1600, 2000 0, 10, 20, 50, 100, 200, 300, 400, 800, 1200, 1600, 2000, 2500 0, 10, 20, 50, 100, 200, 300, 400, 800, 1200, 1600, 2000, 2500, 3000
Max eDTUs choices per database 10, 20, 50, 100, 200, 300, 400, 800, 1200 10, 20, 50, 100, 200, 300, 400, 800, 1200, 1600 10, 20, 50, 100, 200, 300, 400, 800, 1200, 1600, 2000 10, 20, 50, 100, 200, 300, 400, 800, 1200, 1600, 2000, 2500 10, 20, 50, 100, 200, 300, 400, 800, 1200, 1600, 2000, 2500, 3000
Max storage choices per database (GB) 1024 1024 1024 1024 1024

Premium elastic pool limits

eDTUs per pool 125 250 500 1000 1500
Included storage per pool (GB) 250 500 750 1024 1536
Max storage choices per pool (GB) 250, 500, 750, 1024 500, 750, 1024 750, 1024 1024 1536
Max In-Memory OLTP storage per pool (GB) 1 2 4 10 12
Max number DBs per pool 50 100 100 100 100
Max concurrent workers per pool (requests) 200 400 800 1600 2400
Max concurrent sessions per pool 30000 30000 30000 30000 30000
Min eDTUs per database 0, 25, 50, 75, 125 0, 25, 50, 75, 125, 250 0, 25, 50, 75, 125, 250, 500 0, 25, 50, 75, 125, 250, 500, 1000 0, 25, 50, 75, 125, 250, 500, 1000, 1500
Max eDTUs per database 25, 50, 75, 125 25, 50, 75, 125, 250 25, 50, 75, 125, 250, 500 25, 50, 75, 125, 250, 500, 1000 25, 50, 75, 125, 250, 500, 1000, 1500
Max storage per database (GB) 1024 1024 1024 1024 1024

Premium elastic pool limits (continued)

eDTUs per pool 2000 2500 3000 3500 4000
Included storage per pool (GB) 2048 2560 3072 3548 4096
Max storage choices per pool (GB) 2048 2560 3072 3548 4096
Max In-Memory OLTP storage per pool (GB) 16 20 24 28 32
Max number DBs per pool 100 100 100 100 100
Max concurrent workers (requests) per pool 3200 4000 4800 5600 6400
Max concurrent sessions per pool 30000 30000 30000 30000 30000
Min eDTUs choices per database 0, 25, 50, 75, 125, 250, 500, 1000, 1750 0, 25, 50, 75, 125, 250, 500, 1000, 1750 0, 25, 50, 75, 125, 250, 500, 1000, 1750 0, 25, 50, 75, 125, 250, 500, 1000, 1750 0, 25, 50, 75, 125, 250, 500, 1000, 1750, 4000
Max eDTUs choices per database 25, 50, 75, 125, 250, 500, 1000, 1750 25, 50, 75, 125, 250, 500, 1000, 1750 25, 50, 75, 125, 250, 500, 1000, 1750 25, 50, 75, 125, 250, 500, 1000, 1750 25, 50, 75, 125, 250, 500, 1000, 1750, 4000
Max storage per database (GB) 1024 1024 1024 1024 1024

Important

More than 1 TB of storage in the Premium tier is currently available in all regions except the following: West Central US, China East, USDoDCentral, Germany Central, USDoDEast, US Gov SouthWest, Germany NorthEast, USGov Iowa, China North. In other regions, the storage max in the Premium tier is limited to 1 TB. See P11-P15 Current Limitations.

If all DTUs of an elastic pool are used, then each database in the pool receives an equal amount of resources to process queries. The SQL Database service provides resource sharing fairness between databases by ensuring equal slices of compute time. Elastic pool resource sharing fairness is in addition to any amount of resource otherwise guaranteed to each database when the DTU min per database is set to a non-zero value.

Database properties for pooled databases

The following table describes the properties for pooled databases.

Property Description
Max eDTUs per database The maximum number of eDTUs that any database in the pool may use, if available based on utilization by other databases in the pool. Max eDTU per database is not a resource guarantee for a database. This setting is a global setting that applies to all databases in the pool. Set max eDTUs per database high enough to handle peaks in database utilization. Some degree of overcommitting is expected since the pool generally assumes hot and cold usage patterns for databases where all databases are not simultaneously peaking. For example, suppose the peak utilization per database is 20 eDTUs and only 20% of the 100 databases in the pool are peak at the same time. If the eDTU max per database is set to 20 eDTUs, then it is reasonable to overcommit the pool by 5 times, and set the eDTUs per pool to 400.
Min eDTUs per database The minimum number of eDTUs that any database in the pool is guaranteed. This setting is a global setting that applies to all databases in the pool. The min eDTU per database may be set to 0, and is also the default value. This property is set to anywhere between 0 and the average eDTU utilization per database. The product of the number of databases in the pool and the min eDTUs per database cannot exceed the eDTUs per pool. For example, if a pool has 20 databases and the eDTU min per database set to 10 eDTUs, then the eDTUs per pool must be at least as large as 200 eDTUs.
Max storage per database The maximum database size set by the user for a database in a pool. However, pooled databases share allocated pool storage. Even if the total max storage per database is set to be greater than the total available storage space of the pool, the total space actually used by all of the databases will not be able to exceed the available pool limit. Max database size refers to the maximum size of the data files and does not include the space used by log files.

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