Performance enhancement on Azure Premium SSD Disks

Microsoft has announced SSD bursting capabilities. This means that Premium SSD disks can achieve higher peak loads than the maximum IOPS with a new maximum of 3500 IOPS and a bandwidth up to 170 MiB/s. Together with this announcement Microsoft also announced new disk sizes (4, 8 & 16 GiB)


With the new bursting disks you can achieve up to 30 times the provisioned bandwidth, which will give better performance for spiky workloads. Disk bursting is based on a credit system. You will receive bursting credits when traffic is below the provisioned limit. Let me try to explain it using a simple chart.

In this example we will use a P15/256GiB Premium SSD disk with a provisioned speed of 1.100 IOPS and 125 MiB provisioned bandwidth. So Microsoft reserves a speed of 1.100 IOPS (Blue line), but as you can see, the average usage is below that line. So all the blue parts in this line will add bursting credits to the disk. During peak times (3:30 PM – 5:30 PM) credits will be deducted from the disk.

This new capability will help to improve boot times on virtual machines, or increase application workloads during spiky workloads. This is convenient for any unpredictable workload.

Premium Managed SSD disk

Bursting capability is supported on Premium Managed SSD disks only. For existing disks of the applicable sizes, you can enable bursting with either of the two options: detach and re-attach the disk or stop and restart the attached VM. Currently bursting SSD Disks is only available in limited regions, this will increase in the coming months.

Image source: Microsoft announcement


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