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title description services ms.service ms.subservice ms.custom ms.devlang ms.topic author ms.author ms.reviewer ms.date
DTU resource limits elastic pools
This page describes some common DTU resource limits for elastic pools in Azure SQL Database.
sql-database
sql-database
elastic-pools
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conceptual
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07/28/2020

Resources limits for elastic pools using the DTU purchasing model

[!INCLUDEappliesto-sqldb]

This article provides the detailed resource limits for databases in Azure SQL Database that are within an elastic pool using the DTU purchasing model.

Elastic pool: Storage sizes and compute sizes

For Azure 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:

Important

For scaling guidance and considerations, see Scale an elastic pool

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).

For the same number of DTUs, resources provided to an elastic pool may exceed the resources provided to a single database outside of an elastic pool. This means it is possible for the eDTU utilization of an elastic pool to be less than the summation of DTU utilization across databases within the pool, depending on workload patterns. For example, in an extreme case with only one database in an elastic pool where database DTU utilization is 100%, it is possible for pool eDTU utilization to be 50% for certain workload patterns. This can happen even if max DTU per database remains at the maximum supported value for the given pool size.

Note

The storage per pool resource limit in each of the following tables do not include tempdb and log storage.

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 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 1 100 200 500 500 500 500 500 500
Max concurrent workers (requests) per pool 2 100 200 400 600 800 1600 2400 3200
Max concurrent sessions per pool 2 30000 30000 30000 30000 30000 30000 30000 30000
Min DTU per database choices 0, 5 0, 5 0, 5 0, 5 0, 5 0, 5 0, 5 0, 5
Max DTU per database choices 5 5 5 5 5 5 5 5
Max storage per database (GB) 2 2 2 2 2 2 2 2

1 See Resource management in dense elastic pools for additional considerations.

2 For the max concurrent workers (requests) for any individual database, see Single database resource limits. For example, if the elastic pool is using Gen5 and the max vCore per database is set at 2, then the max concurrent workers value is 200. If max vCore per database is set to 0.5, then the max concurrent workers value is 50 since on Gen5 there are a max of 100 concurrent workers per vCore. For other max vCore settings per database that are less 1 vCore or less, the number of max concurrent workers is similarly rescaled.

Standard elastic pool limits

eDTUs per pool 50 100 200 300 400 800
Included storage per pool (GB) 1 50 100 200 300 400 800
Max storage per pool (GB) 500 750 1024 1280 1536 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 2 100 200 500 500 500 500
Max concurrent workers (requests) per pool 3 100 200 400 600 800 1600
Max concurrent sessions per pool 3 30000 30000 30000 30000 30000 30000
Min DTU per database choices 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 DTU per database choices 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

1 See SQL Database pricing options for details on additional cost incurred due to any extra storage provisioned.

2 See Resource management in dense elastic pools for additional considerations.

3 For the max concurrent workers (requests) for any individual database, see Single database resource limits. For example, if the elastic pool is using Gen5 and the max vCore per database is set at 2, then the max concurrent workers value is 200. If max vCore per database is set to 0.5, then the max concurrent workers value is 50 since on Gen5 there are a max of 100 concurrent workers per vCore. For other max vCore settings per database that are less 1 vCore or less, the number of max concurrent workers is similarly rescaled.

Standard elastic pool limits (continued)

eDTUs per pool 1200 1600 2000 2500 3000
Included storage per pool (GB) 1 1200 1600 2000 2500 3000
Max storage per pool (GB) 2560 3072 3584 4096 4096
Max In-Memory OLTP storage per pool (GB) N/A N/A N/A N/A N/A
Max number DBs per pool 2 500 500 500 500 500
Max concurrent workers (requests) per pool 3 2400 3200 4000 5000 6000
Max concurrent sessions per pool 3 30000 30000 30000 30000 30000
Min DTU per database choices 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 DTU per database choices 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 per database (GB) 1024 1024 1024 1024 1024

1 See SQL Database pricing options for details on additional cost incurred due to any extra storage provisioned.

2 See Resource management in dense elastic pools for additional considerations.

3 For the max concurrent workers (requests) for any individual database, see Single database resource limits. For example, if the elastic pool is using Gen5 and the max vCore per database is set at 2, then the max concurrent workers value is 200. If max vCore per database is set to 0.5, then the max concurrent workers value is 50 since on Gen5 there are a max of 100 concurrent workers per vCore. For other max vCore settings per database that are less 1 vCore or less, the number of max concurrent workers is similarly rescaled.

Premium elastic pool limits

eDTUs per pool 125 250 500 1000 1500
Included storage per pool (GB) 1 250 500 750 1024 1536
Max storage per pool (GB) 1024 1024 1024 1024 1536
Max In-Memory OLTP storage per pool (GB) 1 2 4 10 12
Max number DBs per pool 2 50 100 100 100 100
Max concurrent workers per pool (requests) 3 200 400 800 1600 2400
Max concurrent sessions per pool 3 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
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
Max storage per database (GB) 1024 1024 1024 1024 1024

1 See SQL Database pricing options for details on additional cost incurred due to any extra storage provisioned.

2 See Resource management in dense elastic pools for additional considerations.

3 For the max concurrent workers (requests) for any individual database, see Single database resource limits. For example, if the elastic pool is using Gen5 and the max vCore per database is set at 2, then the max concurrent workers value is 200. If max vCore per database is set to 0.5, then the max concurrent workers value is 50 since on Gen5 there are a max of 100 concurrent workers per vCore. For other max vCore settings per database that are less 1 vCore or less, the number of max concurrent workers is similarly rescaled.

Premium elastic pool limits (continued)

eDTUs per pool 2000 2500 3000 3500 4000
Included storage per pool (GB) 1 2048 2560 3072 3548 4096
Max storage 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 2 100 100 100 100 100
Max concurrent workers (requests) per pool 3 3200 4000 4800 5600 6400
Max concurrent sessions per pool 3 30000 30000 30000 30000 30000
Min DTU per database choices 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 DTU per database choices 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

1 See SQL Database pricing options for details on additional cost incurred due to any extra storage provisioned.

2 See Resource management in dense elastic pools for additional considerations.

3 For the max concurrent workers (requests) for any individual database, see Single database resource limits. For example, if the elastic pool is using Gen5 and the max vCore per database is set at 2, then the max concurrent workers value is 200. If max vCore per database is set to 0.5, then the max concurrent workers value is 50 since on Gen5 there are a max of 100 concurrent workers per vCore. For other max vCore settings per database that are less 1 vCore or less, the number of max concurrent workers is similarly rescaled.

Important

More than 1 TB of storage in the Premium tier is currently available in all regions except: China East, China North, Germany Central, and Germany Northeast. In these regions, the storage max in the Premium tier is limited to 1 TB. For more information, 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.

Note

For tempdb limits, see tempdb limits.

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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