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Compute and storage options in Azure Database for PostgreSQL - Flexible Server

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APPLIES TO: Azure Database for PostgreSQL - Flexible Server

You can create an Azure Database for PostgreSQL server in one of three pricing tiers: Burstable, General Purpose, and Memory Optimized. The pricing tiers are differentiated by the amount of compute in vCores that you can provision, the amount of memory per vCore, and the storage technology that's used to store the data. All resources are provisioned at the PostgreSQL server level. A server can have one or many databases.

Resource/Tier Burstable General Purpose Memory Optimized
VM-series B-series Ddsv4-series,
Dsv3-series		 Edsv4-series,
Esv3-series
vCores 1, 2, 4, 8, 12, 16, 20 2, 4, 8, 16, 32, 48, 64 2, 4, 8, 16, 20 (v4), 32, 48, 64
Memory per vCore Variable 4 GB 6.75 GB to 8 GB
Storage size 32 GB to 32 TB 32 GB to 32 TB 32 GB to 32 TB
Database backup retention period 7 to 35 days 7 to 35 days 7 to 35 days

To choose a pricing tier, use the following table as a starting point:

Pricing tier Target workloads
Burstable Workloads that don't need the full CPU continuously.
General Purpose Most business workloads that require balanced compute and memory with scalable I/O throughput. Examples include servers for hosting web and mobile apps and other enterprise applications.
Memory Optimized High-performance database workloads that require in-memory performance for faster transaction processing and higher concurrency. Examples include servers for processing real-time data and high-performance transactional or analytical apps.

After you create a server for the compute tier, you can change the number of vCores (up or down) and the storage size (up) in seconds. You also can independently adjust the backup retention period up or down. For more information, see the Scaling resources section.

Compute tiers, vCores, and server types

You can select compute resources based on the tier, vCores, and memory size. vCores represent the logical CPU of the underlying hardware.

The detailed specifications of the available server types are as follows:

SKU name vCores Memory size Maximum supported IOPS Maximum supported I/O bandwidth
Burstable
B1ms 1 2 GiB 640 10 MiB/sec
B2s 2 4 GiB 1,280 15 MiB/sec
B2ms 2 4 GiB 1,700 22.5 MiB/sec
B4ms 4 8 GiB 2,400 35 MiB/sec
B8ms 8 16 GiB 3,100 50 MiB/sec
B12ms 12 24 GiB 3,800 50 MiB/sec
B16ms 16 32 GiB 4,300 50 MiB/sec
B20ms 20 40 GiB 5,000 50 MiB/sec
General Purpose
D2s_v3 / D2ds_v4 / D2ds_v5 2 8 GiB 3,200 48 MiB/sec
D4s_v3 / D4ds_v4 / D4ds_v5 4 16 GiB 6,400 96 MiB/sec
D8s_v3 / D8ds_v4 / D8ds_v5 8 32 GiB 12,800 192 MiB/sec
D16s_v3 / D16ds_v4 / D16ds_v5 16 64 GiB 20,000 384 MiB/sec
D32s_v3 / D32ds_v4 / D32ds_v5 32 128 GiB 20,000 768 MiB/sec
D48s_v3 / D48ds_v4 / D48ds_v5 48 192 GiB 20,000 900 MiB/sec
D64s_v3 / D64ds_v4 / D64ds_v5 64 256 GiB 20,000 900 MiB/sec
D96ds_v5 96 384 GiB 20,000 900 MiB/sec
Memory Optimized
E2s_v3 / E2ds_v4 / E2ds_v5 2 16 GiB 3,200 48 MiB/sec
E4s_v3 / E4ds_v4 / E4ds_v5 4 32 GiB 6,400 96 MiB/sec
E8s_v3 / E8ds_v4 / E8ds_v5 8 64 GiB 12,800 192 MiB/sec
E16s_v3 / E16ds_v4 / E16ds_v5 16 128 GiB 20,000 384 MiB/sec
E20ds_v4 / E20ds_v5 20 160 GiB 20,000 480 MiB/sec
E32s_v3 / E32ds_v4 / E32ds_v5 32 256 GiB 20,000 768 MiB/sec
E48s_v3 / E48ds_v4 / E48ds_v5 48 384 GiB 20,000 900 MiB/sec
E64s_v3 / E64ds_v4 64 432 GiB 20,000 900 MiB/sec
E64ds_v5 64 512 GiB 20,000 900 MiB/sec
E96ds_v5 96 672 GiB 20,000 900 MiB/sec

Storage

The storage that you provision is the amount of storage capacity available to your Azure Database for PostgreSQL server. The storage is used for the database files, temporary files, transaction logs, and PostgreSQL server logs. The total amount of storage that you provision also defines the I/O capacity available to your server.

Storage is available in the following fixed sizes:

Disk size IOPS
32 GiB Provisioned 120; up to 3,500
64 GiB Provisioned 240; up to 3,500
128 GiB Provisioned 500; up to 3,500
256 GiB Provisioned 1,100; up to 3,500
512 GiB Provisioned 2,300; up to 3,500
1 TiB 5,000
2 TiB 7,500
4 TiB 7,500
8 TiB 16,000
16 TiB 18,000
32 TiB 20,000

Your VM type also constrains IOPS. Even though you can select any storage size independently from the server type, you might not be able to use all IOPS that the storage provides, especially when you choose a server with a small number of vCores.

You can add storage capacity during and after the creation of the server.

Note

Storage can only be scaled up, not down.

You can monitor your I/O consumption in the Azure portal or by using Azure CLI commands. The relevant metrics to monitor are storage limit, storage percentage, storage used, and I/O percentage.

Maximum IOPS for your configuration

SKU name Storage size in GiB 32 64 128 256 512 1,024 2,048 4,096 8,192 16,384 32,767
Maximum IOPS 120 240 500 1,100 2,300 5,000 7,500 7,500 16,000 18,000 20,000
Burstable
B1ms 640 IOPS 120 240 500 640* 640* 640* 640* 640* 640* 640* 640*
B2s 1,280 IOPS 120 240 500 1,100 1,280* 1,280* 1,280* 1,280* 1,280* 1,280* 1,280*
B2ms 1,280 IOPS 120 240 500 1,100 1,700* 1,700* 1,700* 1,700* 1,700* 1,700* 1,700*
B4ms 1,280 IOPS 120 240 500 1,100 2,300 2,400* 2,400* 2,400* 2,400* 2,400* 2,400*
B8ms 1,280 IOPS 120 240 500 1,100 2,300 3,100* 3,100* 3,100* 3,100* 2,400* 2,400*
B12ms 1,280 IOPS 120 240 500 1,100 2,300 3,800* 3,800* 3,800* 3,800* 3,800* 3,800*
B16ms 1,280 IOPS 120 240 500 1,100 2,300 4,300* 4,300* 4,300* 4,300* 4,300* 4,300*
B20ms 1,280 IOPS 120 240 500 1,100 2,300 5,000 5,000* 5,000* 5,000* 5,000* 5,000*
General Purpose
D2s_v3 / D2ds_v4 3,200 IOPS 120 240 500 1,100 2,300 3,200* 3,200* 3,200* 3,200* 3,200* 3,200*
D2ds_v5 3,750 IOPS 120 240 500 1,100 2,300 3,200* 3,200* 3,200* 3,200* 3,200* 3,200*
D4s_v3 / D4ds_v4 / D4ds_v5 6,400 IOPS 120 240 500 1,100 2,300 5,000 6,400* 6,400* 6,400* 6,400* 6,400*
D8s_v3 / D8ds_v4 / D8ds_v5 12,800 IOPS 120 240 500 1,100 2,300 5,000 7,500 7,500 12,800* 12,800* 12,800*
D16s_v3 / D16ds_v4 / D16ds_v5 20,000 IOPS 120 240 500 1,100 2,300 5,000 7,500 7,500 16,000 18,000 20,000
D32s_v3 / D32ds_v4 / D32ds_v5 20,000 IOPS 120 240 500 1,100 2,300 5,000 7,500 7,500 16,000 18,000 20,000
D48s_v3 / D48ds_v4 / D48ds_v5 20,000 IOPS 120 240 500 1,100 2,300 5,000 7,500 7,500 16,000 18,000 20,000
D64s_v3 / D64ds_v4 / D64ds_v5 20,000 IOPS 120 240 500 1,100 2,300 5,000 7,500 7,500 16,000 18,000 20,000
D96ds_v5 20,000 IOPS 120 240 500 1,100 2,300 5,000 7,500 7,500 16,000 18,000 20,000
Memory Optimized
E2s_v3 / E2ds_v4 3,200 IOPS 120 240 500 1,100 2,300 3,200* 3,200* 3,200* 3,200* 3,200* 3,200*
E2ds_v5 3,750 IOPS 120 240 500 1,100 2,300 3,200* 3,200* 3,200* 3,200* 3,200* 3,200*
E4s_v3 / E4ds_v4 / E4ds_v5 6,400 IOPS 120 240 500 1,100 2,300 5,000 6,400* 6,400* 6,400* 6,400* 6,400*
E8s_v3 / E8ds_v4 / E8ds_v5 12,800 IOPS 120 240 500 1,100 2,300 5,000 7,500 7,500 12,800* 12,800* 12,800*
E16s_v3 / E16ds_v4 / E16ds_v5 20,000 IOPS 120 240 500 1100 2,300 5,000 7,500 7,500 16,000 18,000 20,000
E20ds_v4/E20ds_v5 20,000 IOPS 120 240 500 1,100 2,300 5,000 7,500 7,500 16,000 18,000 20,000
E32s_v3 / E32ds_v4 / E32ds_v5 20,000 IOPS 120 240 500 1,100 2,300 5,000 7,500 7,500 16,000 18,000 20,000
E48s_v3 / E48ds_v4 / E48ds_v5 20,000 IOPS 120 240 500 1,100 2,300 5,000 7,500 7,500 16,000 18,000 20,000
E64s_v3 / E64ds_v4 / E64ds_v5 20,000 IOPS 120 240 500 1,100 2,300 5,000 7,500 7,500 16,000 18,000 20,000
E96ds_v5 20,000 IOPS 120 240 500 1,100 2,300 5,000 7,500 7,500 16,000 18,000 20,000

IOPS marked with an asterisk (*) are limited by the VM type that you selected. Otherwise, the selected storage size limits the IOPS.

Note

You might see higher IOPS in the metrics because of disk-level bursting. For more information, see Managed disk bursting.

Maximum I/O bandwidth (MiB/sec) for your configuration

SKU name Storage size in GiB 32 64 128 256 512 1,024 2,048 4,096 8,192 16,384 32,767
Storage bandwidth in MiB/sec 25 50 100 125 150 200 250 250 500 750 900
Burstable
B1ms 10 MiB/sec 10* 10* 10* 10* 10* 10* 10* 10* 10* 10* 10*
B2s 15 MiB/sec 15* 15* 15* 15* 15* 15* 15* 15* 15* 10* 10*
B2ms 22.5 MiB/sec 22.5* 22.5* 22.5* 22.5* 22.5* 22.5* 22.5* 22.5* 22.5* 22.5* 22.5*
B4ms 35 MiB/sec 25 35* 35* 35* 35* 35* 35* 35* 35* 35* 35*
B8ms 50 MiB/sec 25 50 50* 50* 50* 50* 50* 50* 50* 50* 50*
B12ms 50 MiB/sec 25 50 50* 50* 50* 50* 50* 50* 50* 50* 50*
B16ms 50 MiB/sec 25 50 50* 50* 50* 50* 50* 50* 50* 50* 50*
B20ms 50 MiB/sec 25 50 50* 50* 50* 50* 50* 50* 50* 50* 50*
General Purpose
D2s_v3 / D2ds_v4 48 MiB/sec 25 48* 48* 48* 48* 48* 48* 48* 48* 48* 48*
D2ds_v5 85 MiB/sec 25 50 85* 85* 85* 85* 85* 85* 85* 85* 85*
D4s_v3 / D4ds_v4 96 MiB/sec 25 50 96* 96* 96* 96* 96* 96* 96* 96* 96*
D4ds_v5 145 MiB/sec 25 50* 100* 125* 145* 145* 145* 145* 145* 145* 145*
D8s_v3 / D8ds_v4 192 MiB/sec 25 50 100 125 150 192* 192* 192* 192* 192* 192*
D8ds_v5 290 MiB/sec 25 50 100 125 150 200 250 250 290* 290* 290*
D16s_v3 / D16ds_v4 384 MiB/sec 25 50 100 125 150 200 250 250 384* 384* 384*
D16ds_v5 600 MiB/sec 25 50 100 125 150 200 250 250 500 600* 600*
D32s_v3 / D32ds_v4 768 MiB/sec 25 50 100 125 150 200 250 250 500 750 900
D32ds_v5 865 MiB/sec 25 50 100 125 150 200 250 250 500 750 865*
D48s_v3 / D48ds_v4 /D48ds_v5 900 MiB/sec 25 50 100 125 150 200 250 250 500 750 900
D64s_v3 / Dd64ds_v4 /D64ds_v5 900 MiB/sec 25 50 100 125 150 200 250 250 500 750 900
Dd96ds_v5 900 MiB/sec 25 50 100 125 150 200 250 250 500 750 900
Memory Optimized
E2s_v3 / E2ds_v4 48 MiB/sec 25 48* 48* 48* 48* 48* 48* 48* 48* 48* 48*
E2ds_v5 85 MiB/sec 25 50 85* 85* 85* 85* 85* 85* 85* 85* 85*
E4s_v3 / E4ds_v4 96 MiB/sec 25 50 96* 96* 96* 96* 96* 96* 96* 96* 96*
E4ds_v5 145 MiB/sec 25 50* 100* 125* 145* 145* 145* 145* 145* 145* 145*
E8s_v3 / E8ds_v4 192 MiB/sec 25 50 100 125 150 192* 192* 192* 192* 192* 192*
E8ds_v5 290 MiB/sec 25 50 100 125 150 200 250 250 290* 290* 290*
E16s_v3 / E16ds_v4 384 MiB/sec 25 50 100 125 150 200 250 250 384* 384* 384*
E16ds_v5 600 MiB/sec 25 50 100 125 150 200 250 250 500 600* 600*
E20ds_v4 480 MiB/sec 25 50 100 125 150 200 250 250 480* 480* 480*
E20ds_v5 750 MiB/sec 25 50 100 125 150 200 250 250 500 750 750*
E32s_v3 / E32ds_v4 750 MiB/sec 25 50 100 125 150 200 250 250 500 750 750
E32ds_v5 865 MiB/sec 25 50 100 125 150 200 250 250 500 750 865*
E48s_v3 / E48ds_v4 /E48ds_v5 900 MiB/sec 25 50 100 125 150 200 250 250 500 750 900
E64s_v3 / E64ds_v4 /E64ds_v5 900 MiB/sec 25 50 100 125 150 200 250 250 500 750 900
Ed96ds_v5 900 MiB/sec 25 50 100 125 150 200 250 250 500 750 900

I/O bandwidth marked with an asterisk (*) is limited by the VM type that you selected. Otherwise, the selected storage size limits the I/O bandwidth.

Reaching the storage limit

When you reach the storage limit, the server starts returning errors and prevents any further modifications. Reaching the limit might also cause problems with other operational activities, such as backups and write-ahead log (WAL) archiving.

To avoid this situation, the server is automatically switched to read-only mode when the storage usage reaches 95 percent or when the available capacity is less than 5 GiB.

We recommend that you actively monitor the disk space that's in use and increase the disk size before you run out of storage. You can set up an alert to notify you when your server storage is approaching an out-of-disk state. For more information, see Use the Azure portal to set up alerts on metrics for Azure Database for PostgreSQL - Flexible Server.

Storage auto-grow (preview)

Storage auto-grow can help ensure that your server always has enough storage capacity and doesn't become read-only. When you turn on storage auto-grow, the storage will automatically expand without affecting the workload. This feature is currently in preview.

For servers with more than 1 TiB of provisioned storage, the storage autogrow mechanism activates when the available space falls to less than 10% of the total capacity or 64 GiB of free space, whichever of the two values is smaller. Conversely, for servers with storage under 1 TB, this threshold is adjusted to 20% of the available free space or 64 GiB, depending on which of these values is smaller.

As an illustration, take a server with a storage capacity of 2 TiB ( greater than 1 TIB). In this case, the autogrow limit is set at 64 GiB. This choice is made because 64 GiB is the smaller value when compared to 10% of 2 TiB, which is roughly 204.8 GiB. In contrast, for a server with a storage size of 128 GiB (less than 1 TiB), the autogrow feature activates when there's only 25.8 GiB of space left. This activation is based on the 20% threshold of the total allocated storage (128 GiB), which is smaller than 64 GiB.

Azure Database for PostgreSQL - Flexible Server uses Azure managed disks. The default behavior is to increase the disk size to the next premium tier. This increase is always double in both size and cost, regardless of whether you start the storage scaling operation manually or through storage auto-grow. Enabling storage auto-grow is valuable when you're managing unpredictable workloads because it automatically detects low-storage conditions and scales up the storage accordingly.

The process of scaling storage is performed online without causing any downtime, except when the disk is provisioned at 4,096 GiB. This exception is a limitation of Azure Managed disks. If a disk is already 4,096 GiB, the storage scaling activity won't be triggered, even if storage auto-grow is turned on. In such cases, you need to manually scale your storage. Manual scaling is an offline operation that you should plan according to your business requirements.

Remember that storage can only be scaled up, not down.

Limitations

  • Disk scaling operations are always online, except in specific scenarios that involve the 4,096-GiB boundary. These scenarios include reaching, starting at, or crossing the 4,096-GiB limit. An example is when you're scaling from 2,048 GiB to 8,192 GiB.

    This limitation is due to the underlying Azure managed disk, which needs a manual disk scaling operation. You receive an informational message in the portal when you approach this limit.

  • Storage auto-grow currently doesn't work for high-availability or read-replica-enabled servers.

  • Storage auto-grow isn't triggered when you have high WAL usage.

Note

Storage auto-grow never triggers an offline increase.

Backup

The service automatically takes backups of your server. You can select a retention period from a range of 7 to 35 days. To learn more about backups, see Backup and restore in Azure Database for PostgreSQL - Flexible Server.

Scaling resources

After you create your server, you can independently change the vCores, the compute tier, the amount of storage, and the backup retention period. You can scale the number of vCores up or down. You can scale the backup retention period up or down from 7 to 35 days. The storage size can only be increased. You can scale the resources through the Azure portal or the Azure CLI.

Note

After you increase the storage size, you can't go back to a smaller storage size.

When you change the number of vCores or the compute tier, the server is restarted for the new server type to take effect. During the moment when the system switches over to the new server, no new connections can be established, and all uncommitted transactions are rolled back.

The time it takes to restart your server depends on the crash recovery process and database activity at the time of the restart. Restarting typically takes one minute or less. But it can be higher and can take several minutes, depending on transactional activity at the time of the restart. Scaling the storage works the same way and requires a restart.

To improve the restart time, we recommend that you perform scale operations during off-peak hours. That approach reduces the time needed to restart the database server.

Changing the backup retention period is an online operation.

Pricing

For the most up-to-date pricing information, see the Azure Database for PostgreSQL pricing page. The Azure portal shows the monthly cost on the Pricing tier tab, based on the options that you select.

If you don't have an Azure subscription, you can use the Azure pricing calculator to get an estimated price. On the Azure pricing calculator website, select Add items, expand the Databases category, and then select Azure Database for PostgreSQL to customize the options.

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