Azure managed disk types

Applies to: ✔️ Linux VMs ✔️ Windows VMs ✔️ Flexible scale sets ✔️ Uniform scale sets

Azure managed disks currently offers four disk types, each intended to address a specific customer scenario:

  • Ultra disks
  • Premium SSDs (solid-state drives)
  • Standard SSDs
  • Standard HDDs (hard disk drives)

Disk type comparison

The following table provides a comparison of the four disk types to help you decide which 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 4,000 MB/s 900 MB/s 750 MB/s 500 MB/s
Max IOPS 160,000 20,000 6,000 2,000

Ultra disks

Azure ultra disks are the highest-performing storage option for Azure virtual machines (VMs). You can change the performance parameters of an ultra disk without having to restart your VMs. Ultra disks are suited for data-intensive workloads such as SAP HANA, top-tier databases, and transaction-heavy workloads.

Ultra disks must be used as data disks and can only be created as empty disks. Microsoft recommends using premium solid-state drives (SSDs) as operating system (OS) disks.

Ultra disk size

Azure ultra disks offer up to 32 TiB per region per subscription by default, but ultra disks support higher capacity by request. To request an increase in capacity, request a quota increase or contact Azure Support.

The following table provides a comparison of disk sizes and performance caps to help you decide which to use.

Disk Size (GiB) IOPS Cap Throughput Cap (MBps)
4 1,200 300
8 2,400 600
16 4,800 1,200
32 9,600 2,400
64 19,200 4,000
128 38,400 4,000
256 76,800 4,000
512 153,600 4,000
1,024-65,536 (sizes in this range increasing in increments of 1 TiB) 160,000 4,000

Ultra disks are designed to provide submillisecond latencies and target IOPS and throughput described in the preceding table 99.99% of the time.

Ultra disk performance

Ultra disks feature a flexible performance configuration model that allows you to independently configure IOPS and throughput both before and after you provision the disk. Ultra disks come in several fixed sizes, ranging from 4 GiB up to 64 TiB.

Ultra disk IOPS

Ultra disks support IOPS limits of 300 IOPS/GiB, up to a maximum of 160,000 IOPS per disk. To achieve the target IOPS for the disk, ensure that the selected disk IOPS are less than the VM IOPS limit.

The current maximum limit for IOPS for a single VM in generally available sizes is 80,000. Ultra disks with greater IOPS can be used as shared disks to support multiple VMs.

The minimum guaranteed IOPS per disk are 1 IOPS/GiB, with an overall baseline minimum of 100 IOPS. For example, if you provisioned a 4 GiB ultra disk, the minimum IOPS for that disk is 100, instead of eight.

For more information about IOPS, see Virtual machine and disk performance.

Ultra disk throughput

The throughput limit of a single ultra disk is 256 KiB/s for each provisioned IOPS, up to a maximum of 4000 MBps per disk (where MBps = 10^6 Bytes per second). The minimum guaranteed throughput per disk is 4KiB/s for each provisioned IOPS, with an overall baseline minimum of 1 MBps.

You can adjust ultra disk IOPS and throughput performance at runtime without detaching the disk from the virtual machine. After a performance resize operation has been issued on a disk, it can take up to an hour for the change to take effect. Up to four performance resize operations are permitted during a 24-hour window.

It's possible for a performance resize operation to fail because of a lack of performance bandwidth capacity.

Ultra disk limitations

The only infrastructure redundancy options currently available to ultra disks are availability zones. VMs using any other redundancy options cannot attach an ultra disk.

The following table outlines the regions ultra disks are available in, as well as their corresponding availability options.

Note

If a region in the following list lacks availability zones that support ultra disks, then a VM in that region must be deployed without infrastructure redundancy in order to attach an ultra disk.

Redundancy options Regions
Single VMs Australia Central
Brazil South
Central India
East Asia
Germany West Central
Korea Central
North Central US, South Central US, West US
US Gov Arizona, US Gov Texas, US Gov Virginia
Two availability zones France Central
Three availability zones Australia East
Canada Central
North Europe, West Europe
Japan East
Southeast Asia
UK South
Central US, East US, East US 2, West US 2

Not every VM size is available in every supported region with ultra disks. The following table lists VM series which are compatible with ultra disks.

VM Type Sizes Description
General purpose DSv3-series, Ddsv4-series, Dsv4-series, Dasv4-series Balanced CPU-to-memory ratio. Ideal for testing and development, small to medium databases, and low to medium traffic web servers.
Compute optimized FSv2-series High CPU-to-memory ratio. Good for medium traffic web servers, network appliances, batch processes, and application servers.
Memory optimized ESv3-series, Easv4-series, Edsv4-series, Esv4-series, M-series, Mv2-series High memory-to-CPU ratio. Great for relational database servers, medium to large caches, and in-memory analytics.
Storage optimized LSv2-series High disk throughput and IO ideal for Big Data, SQL, NoSQL databases, data warehousing and large transactional databases.
GPU optimized NCv2-series, NCv3-series, NCasT4_v3-series, ND-series, NDv2-series, NVv3-series, NVv4-series Specialized virtual machines targeted for heavy graphic rendering and video editing, as well as model training and inferencing (ND) with deep learning. Available with single or multiple GPUs.
Performance optimized HB-series, HC-series, HBv2-series The fastest and most powerful CPU virtual machines with optional high-throughput network interfaces (RDMA).

Ultra disks cannot be used with some features and functionality, including disk snapshots, disk export, changing disk type, VM images, availability sets, Azure Dedicated Hosts, or Azure disk encryption. Azure Backup and Azure Site Recovery do not support ultra disks. In addition, only un-cached reads and un-cached writes are supported.

Ultra disks support a 4k physical sector size by default. A 512E sector size is available as a generally available offering with no sign-up required. While most applications are compatible with 4k sector sizes, some require 512 byte sector sizes. Oracle Database, for example, requires release 12.2 or later in order to support 4k native disks. For older versions of Oracle DB, 512 byte sector size is required.

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

Premium SSDs

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 SSDs, you can migrate existing VM disks to premium SSDs. Premium SSDs are suitable for mission-critical production applications, but you can use them only with compatible VM series.

To learn more about individual Azure VM types and sizes for Windows or Linux, including size compatibility for premium storage, see Sizes for virtual machines in Azure. You'll need to check each individual VM size article to determine if it is premium storage-compatible.

Premium SSD size

Premium SSD sizes  P1 P2 P3 P4 P6 P10 P15 P20 P30 P40 P50 P60 P70 P80
Disk size in GiB 4 8 16 32 64 128 256 512 1,024 2,048 4,096 8,192 16,384 32,767
Provisioned IOPS per disk 120 120 120 120 240 500 1,100 2,300 5,000 7,500 7,500 16,000 18,000 20,000
Provisioned Throughput per disk 25 MB/sec 25 MB/sec 25 MB/sec 25 MB/sec 50 MB/sec 100 MB/sec 125 MB/sec 150 MB/sec 200 MB/sec 250 MB/sec 250 MB/sec 500 MB/sec 750 MB/sec 900 MB/sec
Max burst IOPS per disk 3,500 3,500 3,500 3,500 3,500 3,500 3,500 3,500 30,000* 30,000* 30,000* 30,000* 30,000* 30,000*
Max burst throughput per disk 170 MB/sec 170 MB/sec 170 MB/sec 170 MB/sec 170 MB/sec 170 MB/sec 170 MB/sec 170 MB/sec 1,000 MB/sec* 1,000 MB/sec* 1,000 MB/sec* 1,000 MB/sec* 1,000 MB/sec* 1,000 MB/sec*
Max burst duration 30 min 30 min 30 min 30 min 30 min 30 min 30 min 30 min Unlimited* Unlimited* Unlimited* Unlimited* Unlimited* Unlimited*
Eligible for reservation No No No No No No No No Yes, up to one year Yes, up to one year Yes, up to one year Yes, up to one year Yes, up to one year Yes, up to one year

*Applies only to disks with on-demand bursting enabled.

Capacity, IOPS, and throughput are guaranteed when a premium storage disk is provisioned. 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 SSDs are designed to provide the single-digit millisecond latencies, target IOPS, and throughput described in the preceding table 99.9% of the time.

Premium SSD bursting

Premium SSDs offer disk bursting, which provides better tolerance on unpredictable changes of IO patterns. Disk bursting is especially useful during OS disk boot and for applications with spiky traffic. To learn more about how bursting for Azure disks works, see Disk-level bursting.

Premium SSD 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 SSDs

Azure standard SSDs are optimized for workloads that need consistent performance at lower IOPS levels. They're an especially good choice for customers with varying workloads supported by on-premises hard disk drive (HDD) solutions. 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 non-production workloads. Like standard HDDs, standard SSDs are available on all Azure VMs.

Standard SSD size

Standard SSD sizes E1 E2 E3 E4 E6 E10 E15 E20 E30 E40 E50 E60 E70 E80
Disk size in GiB 4 8 16 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 500 Up to 500 Up to 500 Up to 2,000 Up to 4,000 Up to 6,000
Throughput per disk Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 400 MB/sec Up to 600 MB/sec Up to 750 MB/sec
Max burst IOPS per disk 600 600 600 600 600 600 600 600 1000
Max burst throughput per disk 150 MB/sec 150 MB/sec 150 MB/sec 150 MB/sec 150 MB/sec 150 MB/sec 150 MB/sec 150 MB/sec 250 MB/sec
Max burst duration 30 min 30 min 30 min 30 min 30 min 30 min 30 min 30 min 30 min

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.

Standard SSD 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 incur a billable cost.

Standard SSD Bursting

Standard SSDs offer disk bursting, which provides better tolerance for the unpredictable IO pattern changes. OS boot disks and applications prone to traffic spikes will both benefit from disk bursting. To learn more about how bursting for Azure disks works, see Disk-level bursting.

Standard HDDs

Azure standard HDDs deliver reliable, low-cost disk support for VMs running latency-tolerant workloads. With standard storage, your data is stored on HDDs, and performance may vary more widely than that of SSD-based disks. Standard HDDs are designed to deliver write latencies of less than 10 ms and read latencies of less than 20 ms for most IO operations. Actual performance may vary depending on IO size and workload pattern, however. 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.

Standard HDD size

Standard Disk Type S4 S6 S10 S15 S20 S30 S40 S50 S60 S70 S80
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 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 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 60 MB/sec Up to 300 MB/sec Up to 500 MB/sec Up to 500 MB/sec

Standard HDD Transactions

For Standard HDDs, each I/O operation is considered as a single transaction, whatever 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 according to their 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 storage offering. For example, you provision an E10 disk and delete it after 20 hours of use. In this case, you're billed for the E10 offering prorated to 20 hours, regardless of the amount of data written to the disk.

Snapshots: Snapshots are billed based on the size used. For example, you create a snapshot of a managed disk with provisioned capacity of 64 GiB and actual used data size of 10 GiB. In this case, 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 performed 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 a single transaction, whatever the I/O size.

For detailed information on pricing for managed disks (including transaction costs), see Managed Disks Pricing.

Ultra disks 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. When you add this capability on the VM, it results in a reservation charge. The reservation charge is only imposed if you enabled ultra disk capability on the VM without an attached ultra disk. When an ultra disk is attached to the ultra disk compatible VM, the reservation 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.

Azure disk reservation

Disk reservation provides you a discount on the advance purchase of one year's of disk storage, reducing your total cost. When you purchase a disk reservation, you select a specific disk SKU in a target region. For example, you may choose five P30 (1 TiB) premium SSDs in the Central US region for a one year term. The disk reservation experience is similar to Azure reserved VM instances. You can bundle VM and Disk reservations to maximize your savings. For now, Azure Disks Reservation offers one year commitment plan for premium SSD SKUs from P30 (1 TiB) to P80 (32 TiB) in all production regions. For more details about reserved disks pricing, see Azure Disks pricing page.

Next steps

See Managed Disks pricing to get started.