For very high demanding workloads, storage wise, Azure has released Ultra Disk performance tier for production use. I’ve already written about it in a previous post ( Slow IOPS in Azure VM’s? not anymore!) But now is the time to take a deeper look.
Which disk types do we have in Azure?
In the following table you can see what the difference is between all disk types in Azure. This table should help you to decide which disk to use for specific workloads.
|Standard HDD||Standard SSD||Premium SSD||Ultra SSD|
|Scenario||Backup, Fileserver, |
|Production and |
|IO intensive |
|Max disk |
|Latency||8 > ms||< 9 ms||1 – 4 ms||<1 ms|
More details about the Ultra SSD disks
As you can see in the above table Azure ultra SSD disk deliver higher throughput, high iOPS and consistent low latency disks for Azure virtual machines. On top of that Ultra SSD disks do have additional benefits that include dynamically changing the performance of the disk, without the need to restart your virtual machine.
When you provision an Ultra SSD disk you can choose what size and performance you want on that specific disk. Here are a few things to keep in mind:
- Disk size: Utra SSD Disks start at 4 GiB up to 64 TiB.
- Disk Max IOPS: For each GiB that you provision you can assign 300 IOPS. So for a 4GiB disk you can reach up to 1200 IOPS, with a maximum of 160.000 IOPS with 1024 GiB and higher.
- Disk Min IOPS: The minimum IOPS per disk is 100, or 2 IOPS per GiB whit disks larger than 50GiB.
- Throughput: Per IOPS the throughput is 4KiB/s, with a minimum of 1 MBps
- Adjustment: Ultra SSD’s allow adjustments in performance to be made on the fly!
|Disk Size||Min IOPS||Max IOPS||Max MBps|
|1.024 – 65.536||2.048 >||160.000||2.000|
Availability and limitations
Since this service is new, it means that this performance tier is not available in all Azure datacenters. Here are some details about Ultra SSD Disks
- Available in the East US 2, SouthEast Asia, and North Europe regions.
- Can only be used with availability zones.
- Only supported on ES / DS v3 Virtual Machines
- Data disks only
- Do not yet support snapshots, Azure backup and site recovery.
Pricing of Ultra SSD Disk is different than other disk types. Ultra SSD is billed based on the provisioned size, provisioned IOPS and provisioned throughput. Azure maps the provisioned size (rounded up) to the nearest disk size offer. Each disk is billed accordingly on an hourly basis. For example, if you provision a 200 GiB Ultra Disk, with 20,000 IOPS and 1,000 MB/second and delete it after 20 hours, it will map to the disk size offer of 256 GiB and you will be billed for the 256 GiB, 20,000 IOPS and 1,000 MB/second for 20 hours. This is regardless of the amount of actual data and number of IOs written to the disk.
Below you will find the prices directly from the Microsoft website:
$0.000164 per GiB/hour
$0.000068 per provisioned IOPS/hour
$0.00137 per provisioned MB/s/hour
$0.006 per vcpu/hour provisioned reservation charge.
This reservation charge is only imposed if you enable Ultra Disk compatibility on the VM without attaching an Ultra Disk.
More information and sources:
How to deploy Azure ultra disks: https://docs.microsoft.com/bs-latn-ba/azure/virtual-machines/windows/disks-enable-ultra-ssd
Information from Microsoft on testings: https://azure.microsoft.com/en-us/blog/mission-critical-performance-with-ultra-ssd-for-sql-server-on-azure-vm/