What disk types are available in Azure?
Azure managed disks currently offers four disk types, each type is aimed towards specific customer scenarios.
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|
|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 MB/s||900 MB/s||750 MB/s||500 MB/s|
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.
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 guaranteed 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 guaranteed 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 (GiB)||IOPS Cap||Throughput Cap (MBps)|
|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:
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:
If a region in the following list has no ultra disk capable availability zones, then VMs in that region must be deployed without any infrastructure redundancy options in order to attach an ultra disk.
|Regions||Number of availability zones supporting ultra disks|
|US Gov Virginia||None|
|South Central US||None|
|Central US||Three zones|
|West US 2||Three zones|
|East US||Three zones|
|East US 2||Two zones|
|SouthEast Asia||Three zones|
|North Europe||Three zones|
|West Europe||Three zones|
|UK South||Three zones|
|Japan East||Two zones|
|France Central||Two zones|
- Are only supported on the following VM series:
- Not every VM size is available in every supported region with ultra disks
- Are only available as data disks and only support 4k physical sector size. Due to the 4K native sector size of Ultra Disk, there are some applications that won't be compatible with ultra disks. One example would be Oracle Database, which requires release 12.2 or later in order to support ultra disks.
- Can only be created as empty disks
- Doesn't currently support disk snapshots, VM images, availability sets, Azure Dedicated Hosts, or Azure disk encryption
- Doesn't currently support integration with Azure Backup or Azure Site Recovery
- Only supports un-cached reads and un-cached writes
- The current maximum limit for IOPS on GA VMs is 80,000.
Azure ultra disks offer up to 16 TiB per region per subscription by default, but ultra disks support higher capacity by request. To request an increase in capacity, contact Azure Support.
If you would like to start using ultra disks, see our article on the subject: Using Azure ultra disks.
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. From either of those articles, you need to check each individual VM size article to determine if it is premium storage-compatible.
|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|
|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|
|Max burst duration||30 min||30 min||30 min||30 min||30 min||30 min||30 min||30 min|
|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|
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.
Premium SSD sizes smaller than P30 now offer disk bursting and can burst their IOPS per disk up to 3,500 and their bandwidth up to 170 Mbps. Bursting is automated and operates based on a credit system. Credits are automatically accumulated in a burst bucket when disk traffic is below the provisioned performance target and credits are automatically consumed when traffic bursts beyond the target, up to the max burst limit. The max burst limit defines the ceiling of disk IOPS & Bandwidth even if you have burst credits to consume from. Disk bursting provides better tolerance on unpredictable changes of IO patterns. You can best leverage it for OS disk boot and applications with spiky traffic.
Disks bursting support will be enabled on new deployments of applicable disk sizes by default, with no user action required. For existing disks of the applicable sizes, you can enable bursting with either of two the options: detach and reattach the disk or stop and restart the attached VM. All burst applicable disk sizes will start with a full burst credit bucket when the disk is attached to a Virtual Machine that supports a max duration at peak burst limit of 30 mins. To learn more about how bursting work on Azure Disks, see Premium SSD bursting.
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.
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.
|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|
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.
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.
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.
|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|
For Standard HDDs, each IO operation is considered as a single transaction, regardless of the I/O size. These transactions have a billing impact.
When using managed disks, the following billing considerations apply:
- Disk type
- managed disk Size
- 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 storage offering. 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.
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 is the option to purchase one year of disk storage in advance at a discount, reducing your total cost. When purchasing a disk reservation, you select a specific Disk SKU in a target region, for example, 10 P30 (1TiB) premium SSDs in East US 2 region for a one year term. The reservation experience is similar to reserved virtual machine (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 (1TiB) to P80 (32 TiB) in all production regions. For more details on the Reserved Disks pricing, see Azure Disks pricing page.