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Azure–Single Instance VMs with 99.9% SLA

When Microsoft introduced their IAAS offering on Azure, the general rule to have a 99.9% SLA was to have at least 2 VMs provisioned. Most of my customers who I talk to today remember this rule and think that it still applies. Where in fact, there is since 2016 an option to provide a single instance VM and have the 99.9% SLA guarantee too!

The biggest requirement to achieve the 99.9% SLA guarantee for a single instance VM is to use Premium Storage. Premium Storage offers a much higher level of availability and performance with 5,000 IOPS per disk, versus 500 IOPS per disk with Standard Storage. The way Premium storage offers this is by utilizing SSD storage drives within the data center that are located on the same server hardware where the VM is running. Premium storage also offers a much higher throughput rate per disk of 2 Gbps.

Why should I still prefer multi-instance VMs?

It can still be adventagous to use a multi-instance VM configuration, because the SLA is a higher(99.95%). And of course your architecture is easier to scale horizontally.

More information: Azure SLA for Virtual Machines

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