If you have deployed the Virtual Machines on azure, you must know that we needed a storage account to store the VHDs for the Virtual machine and based on that Images/VHDs we provision a VM.
With the old traditional deployment along with the hustle of managing the Storage account there were few limitations as well :
- Only 40 disk per storage account and 20 storage account per subscription so we can have maximum 20 *40 = 800 VMs per subscription with the old approach.
- With each Storage account there comes a limitation of 20,000 IOPS limit.
Introducing Managed Disk
With Managed Disks, Microsoft is taking away the hustle of managing Storage Account on your behalf; you don’t need to create storage accounts for virtual machine disks anymore. You can deploy standard (HDD) or premium (SSD) Managed Disks, with LRS fault tolerance (3 copies in a single datacenter),GRS option is not yet supported though. This lifting is achieved by the fact, that Azure manages the placement of the managed disks in the background to one or more storage accounts. You will not see the storage accounts anymore, only the disks which belong to the VMs.
Resolving the Limitations
You don’t have to worry about the 20,000 IOPS limit of a storage account anymore; just deploy more virtual machines with Managed Disks, and Azure handles the placement of your disks.
If you are creating your own generalized images, then you don’t have to copy them to multiple storage accounts anymore – you simply store the image (a virtual hard disk) in a single storage account (as a blob) in each required region.
You can have up to 10,000 Managed Disks in a single Azure subscription – it’s 2,000 by default but you can have it increased by calling Microsoft Support. If you are into on-demand scaling, then virtual machine scale sets (VMSS) can handle up to 1,000 virtual machines with Managed Disks.
Azure Storage manages how disk size and I/O capacity are assigned to applications by load balancing data based on the traffic generated by an app, so as demand grows, Azure Storage adds disk capacity as required. While primarily intended for cloud apps, Azure Storage can also be used by apps running on local devices and on-premises servers. For high-performance workloads, the Premium Storage tier provides low-latency disk support for Azure-based VMs.
Microsoft has learnt over the years from the client solutions and used the best practices with the Availability set and make sure to give you high availability out of box. One disk is attached to one VM which makes availability much higher
Managed Disks is the feature where Microsoft is taking care of all the hassle of using a storage account and by using the best practices. It will gives us more power and flexibility by removing the limitations of 20,000 IOPS per storage account. Also, with 20 storage account and 40 images in one storage account it was a limitation which is now resolved and you can have 10,000 Managed Disks in one azure subscription.