What disk types are available in Azure?

Azure managed disks currently offers four disk types, each type is aimed towards specific customer scenarios.

Disk comparison

The following table provides a comparison of ultra disks, premium solid-state-drives (SSD), standard SSD, and standard hard disk drives (HDD) for managed disks to help you decide what to use.

Ultra disk Premium SSD Standard SSD Standard HDD
Disk type SSD SSD SSD HDD
Scenario IO-intensive workloads such as SAP HANA, top tier databases (for example, SQL, Oracle), and other transaction-heavy workloads. Production and performance sensitive workloads Web servers, lightly used enterprise applications and dev/test Backup, non-critical, infrequent access
Max disk size 65,536 gibibyte (GiB) 32,767 GiB 32,767 GiB 32,767 GiB
Max throughput 2,000 MiB/s 900 MiB/s 750 MiB/s 500 MiB/s
Max IOPS 160,000 20,000 6,000 2,000

Ultra disk

Azure ultra disks deliver high throughput, high IOPS, and consistent low latency disk storage for Azure IaaS VMs. Some additional benefits of ultra disks include the ability to dynamically change the performance of the disk, along with your workloads, without the need to restart your virtual machines (VM). Ultra disks are suited for data-intensive workloads such as SAP HANA, top tier databases, and transaction-heavy workloads. Ultra disks can only be used as data disks. We recommend using premium SSDs as OS disks.

Performance

When you provision an ultra disk, you can independently configure the capacity and the performance of the disk. Ultra disks come in several fixed sizes, ranging from 4 GiB up to 64 TiB, and feature a flexible performance configuration model that allows you to independently configure IOPS and throughput.

Some key capabilities of ultra disks are:

  • Disk capacity: Ultra disks capacity ranges from 4 GiB up to 64 TiB.
  • Disk IOPS: Ultra disks support IOPS limits of 300 IOPS/GiB, up to a maximum of 160 K IOPS per disk. To achieve the IOPS that you provisioned, ensure that the selected Disk IOPS are less than the VM IOPS limit. The minimum IOPS per disk is 2 IOPS/GiB, with an overall baseline minimum of 100 IOPS. For example, if you had a 4 GiB ultra disk, you will have a minimum of 100 IOPS, instead of eight IOPS.
  • Disk throughput: With ultra disks, the throughput limit of a single disk is 256 KiB/s for each provisioned IOPS, up to a maximum of 2000 MBps per disk (where MBps = 10^6 Bytes per second). The minimum throughput per disk is 4KiB/s for each provisioned IOPS, with an overall baseline minimum of 1 MBps.
  • Ultra disks support adjusting the disk performance attributes (IOPS and throughput) at runtime without detaching the disk from the virtual machine. Once a disk performance resize operation has been issued on a disk, it can take up to an hour for the change to actually take effect. There is a limit of four performance resize operations during a 24 hour window. It is possible for a performance resize operation to fail due to a lack of performance bandwidth capacity.

Disk size

Disk Size (GiB) IOPS Cap Throughput Cap (MBps)
4 1,200 300
8 2,400 600
16 4,800 1,200
32 9,600 2,000
64 19,200 2,000
128 38,400 2,000
256 76,800 2,000
512 80,000 2,000
1,024-65,536 (sizes in this range increasing in increments of 1 TiB) 160,000 2,000

GA scope and limitations

For now, ultra disks have additional limitations, they are as follows:

  • Are supported in East US 2, SouthEast Asia, and North Europe, in two availability zones per region
  • Can only be used with availability zones (availability sets and single VM deployments outside of zones will not have the ability to attach an ultra disk)
  • Are only supported on ES/DS v3 VMs
  • Are only available as data disks and only support 4k physical sector size
  • Can only be created as empty disks
  • Do not yet support disk snapshots, VM images, availability sets, virtual machine scale sets, and Azure disk encryption
  • Do not yet support integration with Azure Backup or Azure Site Recovery
  • The current maximum limit for IOPS on GA VMs is 80,000.

If you would like to start using ultra disks, see our article on the subject: Using Azure ultra disks.

Premium SSD

Azure premium SSDs deliver high-performance and low-latency disk support for virtual machines (VMs) with input/output (IO)-intensive workloads. To take advantage of the speed and performance of premium storage disks, you can migrate existing VM disks to Premium SSDs. Premium SSDs are suitable for mission-critical production applications. Premium SSDs can only be used with VM series that are premium storage-compatible.

To learn more about individual VM types and sizes in Azure for Windows, including which sizes are premium storage-compatible, see Windows VM sizes. To learn more about individual VM types and sizes in Azure for Linux, including which sizes are premium storage-compatible, see Linux VM sizes.

Disk size

Premium SSD sizesĀ  P4 P6 P10 P15 P20 P30 P40 P50 P60 P70 P80
Disk size in GiB 32 64 128 256 512 1,024 2,048 4,096 8,192 16,384 32,767
IOPS per disk 120 240 500 1,100 2,300 5,000 7,500 7,500 16,000 18,000 20,000
Throughput per disk 25 MiB/sec 50 MiB/sec 100 MiB/sec 125 MiB/sec 150 MiB/sec 200 MiB/sec 250 MiB/sec 250 MiB/sec 500 MiB/sec 750 MiB/sec 900 MiB/sec

When you provision a premium storage disk, unlike standard storage, you are guaranteed the capacity, IOPS, and throughput of that disk. For example, if you create a P50 disk, Azure provisions 4,095-GB storage capacity, 7,500 IOPS, and 250-MB/s throughput for that disk. Your application can use all or part of the capacity and performance. Premium SSD disks are designed to provide low single-digit millisecond latencies and target IOPS and throughput described in the preceding table 99.9% of the time.

Transactions

For premium SSDs, each I/O operation less than or equal to 256 KiB of throughput is considered a single I/O operation. I/O operations larger than 256 KiB of throughput are considered multiple I/Os of size 256 KiB.

Standard SSD

Azure standard SSDs are a cost-effective storage option optimized for workloads that need consistent performance at lower IOPS levels. Standard SSD offers a good entry level experience for those who wish to move to the cloud, especially if you experience issues with the variance of workloads running on your HDD solutions on premises. Compared to standard HDDs, standard SSDs deliver better availability, consistency, reliability, and latency. Standard SSDs are suitable for Web servers, low IOPS application servers, lightly used enterprise applications, and Dev/Test workloads. Like standard HDDs, standard SSDs are available on all Azure VMs.

Disk size

Standard SSD sizes E4 E6 E10 E15 E20 E30 E40 E50 E60 E70 E80
Disk size in GiB 32 64 128 256 512 1,024 2,048 4,096 8,192 16,384 32,767
IOPS per disk Up to 120 Up to 240 Up to 500 Up to 500 Up to 500 Up to 500 Up to 500 Up to 500 Up to 2,000 Up to 4,000 Up to 6,000
Throughput per disk Up to 25 MiB/sec Up to 50 MiB/sec Up to 60 MiB/sec Up to 60 MiB/sec Up to 60 MiB/sec Up to 60 MiB/sec Up to 60 MiB/sec Up to 60 MiB/sec Up to 400 MiB/sec Up to 600 MiB/sec Up to 750 MiB/sec

Standard SSDs are designed to provide single-digit millisecond latencies and the IOPS and throughput up to the limits described in the preceding table 99% of the time. Actual IOPS and throughput may vary sometimes depending on the traffic patterns. Standard SSDs will provide more consistent performance than the HDD disks with the lower latency.

Transactions

For standard SSDs, each I/O operation less than or equal to 256 KiB of throughput is considered a single I/O operation. I/O operations larger than 256 KiB of throughput are considered multiple I/Os of size 256 KiB. These transactions have a billing impact.

Standard HDD

Azure standard HDDs deliver reliable, low-cost disk support for VMs running latency-insensitive workloads. With standard storage, the data is stored on hard disk drives (HDDs). Latency, IOPS and Throughput of Standard HDD disks may vary more widely as compared to SSD-based disks. Standard HDD Disks are designed to deliver write latencies under 10ms and read latencies under 20ms for most IO operations, however the actual performance may vary depending on the IO size and workload pattern. When working with VMs, you can use standard HDD disks for dev/test scenarios and less critical workloads. Standard HDDs are available in all Azure regions and can be used with all Azure VMs.

Disk size

Standard Disk Type S4 S6 S10 S15 S20 S30 S40 S50 S60 S70 S80
Disk sizeĀ in GiB 32 64 128 256 512 1,024 2,048 4,096 8,192 16,384 32,767
IOPS per disk Up to 500 Up to 500 Up to 500 Up to 500 Up to 500 Up to 500 Up to 500 Up to 500 Up to 1,300 Up to 2,000 Up to 2,000
Throughput per disk Up to 60 MiB/sec Up to 60 MiB/sec Up to 60 MiB/sec Up to 60 MiB/sec Up to 60 MiB/sec Up to 60 MiB/sec Up to 60 MiB/sec Up to 60 MiB/sec Up to 300 MiB/sec Up to 500 MiB/sec Up to 500 MiB/sec

Transactions

For Standard HDDs, each IO operation is considered as a single transaction, regardless of the I/O size. These transactions have a billing impact.

Billing

When using managed disks, the following billing considerations apply:

  • Disk type
  • managed disk Size
  • Snapshots
  • Outbound data transfers
  • Number of transactions

Managed disk size: managed disks are billed on the provisioned size. Azure maps the provisioned size (rounded up) to the nearest offered disk size. For details of the disk sizes offered, see the previous tables. Each disk maps to a supported provisioned disk size offering and is billed accordingly. For example, if you provisioned a 200 GiB Standard SSD, it maps to the disk size offer of E15 (256 GiB). Billing for any provisioned disk is prorated hourly by using the monthly price for the Premium Storage offer. For example, if you provisioned an E10 disk and deleted it after 20 hours, you're billed for the E10 offering prorated to 20 hours. This is regardless of the amount of actual data written to the disk.

Snapshots: Snapshots are billed based on the size used. For example, if you create a snapshot of a managed disk with provisioned capacity of 64 GiB and actual used data size of 10 GiB, the snapshot is billed only for the used data size of 10 GiB.

For more information on snapshots, see the section on snapshots in the managed disk overview.

Outbound data transfers: Outbound data transfers (data going out of Azure data centers) incur billing for bandwidth usage.

Transactions: You're billed for the number of transactions that you perform on a standard managed disk. For standard SSDs, each I/O operation less than or equal to 256 KiB of throughput is considered a single I/O operation. I/O operations larger than 256 KiB of throughput are considered multiple I/Os of size 256 KiB. For Standard HDDs, each IO operation is considered as a single transaction, regardless of the I/O size.

For detailed information on pricing for Managed Disks, including transaction costs, see Managed Disks Pricing.

Ultra disk VM reservation fee

Azure VMs have the capability to indicate if they are compatible with ultra disks. An ultra disk compatible VM allocates dedicated bandwidth capacity between the compute VM instance and the block storage scale unit to optimize the performance and reduce latency. Adding this capability on the VM results in a reservation charge that is only imposed if you enabled ultra disk capability on the VM without attaching an ultra disk to it. When an ultra disk is attached to the ultra disk compatible VM, this charge would not be applied. This charge is per vCPU provisioned on the VM.

Note

For constrained core VM sizes, the reservation fee is based on the actual number of vCPUs and not the constrained cores. For Standard_E32-8s_v3, the reservation fee will be based on 32 cores.

Refer to the Azure Disks pricing page for ultra disk pricing details.