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.

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Azure Ultra Disk performance storage now available!

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 HDDStandard SSDPremium SSDUltra SSD
ScenarioBackup, Fileserver,
infrequent access
lightly used
applications and
dev/test systems
Production and
IO intensive
Max disk
Latency8 > ms< 9 ms1 – 4 ms<1 ms
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Slow IOPS in Azure VM’s? not anymore!

— UPDATE 31-12-2019 — New disk sizes P1-P3 & E1-E3

In Azure there are several ways to implement your VM storage. I get a lot of complaints about slow storage in Azure. In this article I will try to explain why this might be slow, and what you can do about it. There are multiple locations where the limit might be hit. So I will address all in the following topics.

Virtual machine type

The first limitation might be coming from your virtual machine. Each type has its own total IOPS limit. Thus by adding more disk or faster disk than the type and size allows will not make any speed difference in the end. One of the obvious reasons for faster disk performance is to use SSD disks instead of HDD.

Example of an IOPS limit on VM type

But keep in mind, not all virtual machines do support Premium SSD Storage, with an effective limit of 500 IOPS per disk, like in the Av2 series. And then there is host caching, that effects performance as well. A few examples:

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