azure sql vm Archives - John McCormack DBA

My final tip in my series 7 ways for data teams to save money in Azure is to delete unused instances (and orphaned storage) to save money in Azure.

Delete unused instances

It’s easy to spin up instances in Azure, especially for developers if you haven’t implemented a tight permissions policy. Pet projects and Proof of Concepts (POCs) get created regularly and the person involved needs to remember to delete all resources or else you will be charged indefinitely.

Even services which can be stopped and deallocated such as Virtual Machines will cost you money if they are not deleted. Why? If you don’t delete unused instances in Azure, you still pay for all of the associated costs including the storage which can be significant. Moreover, you need to specifically delete your storage when your delete those VMs or you’ll keep paying for that too. That is known as orphaned storage or unattached storage, and it is not cheap.

A script to find unattached storage

Microsoft published a PowerShell script to find unattached storage in azure which you can run to list out anywhere it occurs in your subscriptions.

Use resource groups for POCs

I would encourage developers and engineers to use a resource group for POCs. This way, when it is done, the whole resource group can be obliterated in one go, leaving nothing behind.

Azure policies and tagging

Once you have got rid of all your old unused instances and orphaned storage, you may want to prevent team members from doing the same thing again. This is where a combination of Azure policies and tagging comes in handy. You can set policies to prevent new services being spun up without the appropriate tags. This Microsoft tutorial explains how to manage tag governance with Azure Policy.

This post on how to save money with Azure Reserved instances is part of a 7 part series on cost optimisation with Azure.

Save with reserved instances

Did you say “Save 73% with reserved instances”? I did. In fact, Azure even advertise you can save up to 80% if you combine reserved instances (RI) with Azure Hybrid Benefit (AHB). So what do we mean by reserved instances?

What is a reserved instance?

A reserved instance is a way of reserving capacity in Azure. You are offered a discount by agreeing to a 1 or 3 year commitment. You can choose to pay an element up from to reduce your monthly bill, or you can just pay monthly. Paying monthly does not cost more than paying a portion of the cost upfront so it comes down to a preference for you or your company. Savings are made against compute costs, but not licence costs such as SQL Server Enterprise.

When would I reserve

If you know that you would need an instance for 12 months or longer, it is usually worth taking a reserved instance. A typical scenario for this would be a production SQL Server running in Azure VM or a production SQL Database. If you have a stable workload that you don’t see changing in the near future, reservations are a good bet.

Save with Reserved Instances (Examples)

For this example, you are running SQL Server enterprise on E8s 4s VMs in UK West. You have a cluster of 3 to support your availability groups.

Reservation	Compute cost	Windows licence cost	SQL licence cost	Total monthly cost
Pay as you go	£995.66	£600.66	£4,896.68	£6,493.04
1 yr reserved	£587.31	£600.66	£4,896.68	£6,084.65
3 yr reserved	£378.25	£600.66	£4,896.68	£5,875.59

_{^{3 x E8s v4 (8 vCPUs, 64 GB RAM); Windows – SQL Server; 3 year reserved; 0 managed OS disks – S4, 100 transaction units; Inter-region transfer type, 5 GB outbound data transfer from UK West to East Asia}}

Alternatively, look at the potential savings with Azure SQL DB. In this example, we are looking at a SQL DB, 8 vCore provisioned instance in UK West on General Purpose tier.

Reservation	Compute cost	SQL licence cost	Total monthly cost
Pay as you go	£828.17	£435.11	£1,263.29
1 yr reserved	£538.11	£435.11	£973.22
3 yr reserved	£372.67	£435.11	£807.78

^{1 x Single Database, vCore, RA-GRS backup storage, General Purpose, Provisioned, Gen 5, Local redundancy, 1 8 vCore instance(s) x 730 Hours, 32 GB Storage, 0 GB backup storage}

I hesitated to put prices on here because they will change more frequently than I can update the blog but it gives you a general idea. For up to date pricing, please always refer to the Azure Pricing Calculator.

Reserved Instance Allocation

Thankfully, you don’t need to specify which instance uses the allocation, it is just available at an hourly grain level. If you have a live instance that matches your reservation, the reservation credits are used for billing. If you drop an instance and you have another eligible instance type, it will automatically uses the allocation. The allocation is on a use it or lose it basis. If you have a reservation but no suitable resource to use the allocation, you lose it. If you have more instances than reservations, you pay on PAYG terms for anything above your reservation levels.

What type of resources can I reserve

As this post is directed at Azure SQL Data professionals; it is worth pointing out Virtual machines, SQL Database, Azure Synapse Analytics and Azure Blob Storage. It’s also encouraging to see discounts available for MySQL, MariaDB and PostgreSQL.

Azure services eligible to be reserved instances

What if my needs change?

Despite being a long term commitment, Reserved Instances are fairly flexible as Microsoft acknowledges that customers’ needs will change from time to time. You can exchange or cancel reservations as your needs change up to limits imposed by Microsoft.

Delete unused instances to save money in Azure