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Intro

This blogpost series will look into how to get the most disk performance from you Azure VM.

 

Background

Disk performance in Azure is very important for the overall experience of an application running on a VM hosted in Azure. It’s not always as easy as just choosing the most expensive disk and you will get the best performance. Therefore I will try to share my experience in gaining optimal performance within the given budget. And finally some tools for measuring if your chosen setup really delivers what’s expected.

 

Azure VMs can be configured with either HDD (Normal spinning disks) called standard or “SSD” disks called premium.

 

These disks can be attached to the VM as managed disks or unmanged disks.

 

The maximum disk size you can attach to a VM is 1024 GB. It will soon be expanded to 4 TB, but if you need performance you still want to read this post.

If you need larger disks in windows than available to you, you can use storage pools and storage spaces direct to gain size and performance.

 

  • Managed disks are the new Azure feature where all new features will be available.
  • Unmanaged standard disks can have an price advantage if you have many disks with large areas of free space.

 

Performance metrics

First lets have a look at what you get in terms of performance from the different options you have.

 

Unmanged disks – IOPS and throughput:

Standard LRS:
1 GB – 500 IOPS / 60 MB/s
Ex.
32 GB – 500 IOPS / 60 MB/s
64 GB – 500 IOPS / 60 MB/s
1024 GB – 500 IOPS / 60 MB/s
Premium:
P10 (128 GB) – 500 IOPS / 100 MB/s
P20 (512 GB) – 2300 IOPS / 150 MB/s
P30 (1024 GB) – 5000 IOPS / 200 MB/s

 

Managed disks – IOPS and throughput:

Standard:
S4 (32 GB) – 500 IOPS / 60 MB/s
S6 (64 GB) – 500 IOPS / 60 MB/s
S10 (128 GB) – 500 IOPS / 60 MB/s
S20 (512 GB) – 500 IOPS / 60 MB/s
S30 (1024 GB) – 500 IOPS / 60 MB/s
Premium:
P10 (128 GB) – 500 IOPS / 100 MB/s
P20 (512 GB) – 2300 IOPS / 150 MB/s
P30 (1024 GB) – 5000 IOPS / 200 MB/s

VM Sizes include a maximum number of attached disks and total IO limitation. Be aware of this when choosing VM size if you plan to use more disks.

 

Look for these when deploying VM’s.


D1_V2 VM with only Standard disks and max 2.

DS3_V2 VM with support for 8 premium disks.

You find all VM sizes and max IOPS / Throughput here:

Look for “Max data disks” and “Max uncached Disk throughout”

 

Prices

When using Standard unmanged disks you only pay for the capacity you use. When using premium unmanged disk and managed disks (Std and premium) you pay for the whole allocated capacity.

 

Unmanaged disk prices in west EU pr. 10/5/2017

Standard LRS:
1 GB – 0,05 USD / month
Ex.
32 GB – 1,6 USD / month (when all GB used)
64 GB – 3,5 USD / month (when all GB used)
1024 GB – 51,2 USD / month (when all GB used)
Premium:
P10 (128 GB) – 21,68 USD / month
P20 (512 GB) – 80,54 USD / month
P30 (1024 GB) – 148,68 USD / month

Managed disk prices in west EU pr. 10/5/2017

Standard:
S4 (32 GB) – 0,77 USD / month
S6 (64 GB) – 1,5 USD / month
S10 (128 GB) – 2,94 USD / month
S20 (512 GB) – 10,88 USD / month
S30 (1024 GB) – 20,48 USD / month
Premium:
P10 (128 GB) – 21,68 USD / month
P20 (512 GB) – 80,54 USD / month
P30 (1024 GB) – 148,68 USD / month

Be aware when assigning disks to VM’s. Size is adjustable but billing and performance will be in the described tiers. Eg. 600 gb Premium disk is billed and performing as P30.

 

SSD’s are more expensive than HDD bud does maybe not give you what you would expect from a local attached physical SSD.

Small SSD’s have the same IOPS performance as normal HDD’s.

Azure disks come in various sizes and prices. Always know you options and demands before deploying an application.

Whats next

In the next post in this series I will take a look at how to do the best price / performance disk layout using windows storage pool etc. and how to measure which performance you really get from the different configurations.

 

Klaus G. Nielsen
kgn@gammelbys.com
https://www.linkedin.com/in/klaus-gjelstrup-nielsen