Managed Share Disk in Azure

Azure shared disks is a new feature for Azure managed disks that allows you to attach a managed disk to multiple virtual machines (VMs) simultaneously. Attaching a managed disk to multiple VMs allows you to either deploy new or migrate existing clustered applications to Azure

Absence of shared disks was one of the limitation in Azure for those who wish to migrate their clustered compute resources into Azure. Ex: SQL Always on availability group with failover cluster.

The alternative option was create Azure Files and mount it into multiple virtual machines which provides a "shared file system" for the applications however it is suitable for the clustered environment.

Thanks to Azure team for bringing this new feature which will be helpful for those who wish to lift and shift the clustered environments into Azure compute.

The concept of Azure shared disk is similar to accessing storage blocks/volume via ISCSI as a LUN created in the SAN storage. SCSI PR(Persistent reservation) is an industry standard leveraged by applications running on Storage Area Network (SAN) on-premises.

Azure shared disk is now generally available in all regions however with some limitations; hopefully these limitations will be overcome in near future.

I will take you through step by step install and configure of Azure disk in brief, here we go.

Azure Shared Disk

Create a shared disk

Input the disk name and relevant information --> Change disk size

Only Premium SSD and Ultra SSD disks from 256 GB size supports disk sharing, choose the appropraite disk based on the requirement. Here i'm going to select 256 GB disk which is having share capacity of 2 ie, can be added into virtual machine, suitable for 2 node clusters.

I'm leaving all other settings to default.

On Advanced tab click on "Enable Shared disk" yes check box and select the number of shares, here the maximum is 2 so keeping the default value. If you have choose a shared disk with 5 shares; max shares can be opt from this window.

Validate and create the shared disk

Create 2 Virtual Machines

Create 2 virtual machines based on your flavour to test the shared disk attachment, here I've created 2 windows server 2016 VM's to build 2 node windows failover cluster.

Virtual Machine 1 - fsclusternode01

Virtual Machine 2 - fsclusternode02

Attach Shared Disk

Shared disk cannot be attached to the 2 virtual machines when it is turned on, so stop the virtual machines before attaching the shared disk.

Navigate to virtual machines --> Disks --> click on "attach existing disks" from under Data disks menu

Select the shared disk which we have created from the drop down menu and change the host cache to read/write, then save .

Perform the same on the 2nd virtual machine "fsclusternode02"

Start the virtual machines one by one; note that better avoid starting both virtual machines at same time instead start it one by one.

LLogin to each virtual machine and verify that the shared disk is attached successfully, open disk management (run --> diskmgmt.msc) to verify the disk status.

Install and configure windows failover cluster on VM's

Install windows server failover cluster feature into the virtual machines.

Once the feature is ready open failover cluster manager and create a cluster without adding disks

Refer the article below if you are not familiar with WSFC.

https://docs.microsoft.com/en-us/windows-server/failover-clustering/create-failover-cluster

Go back to the disk management and initialise the shared disk and bring it online, then create a new simple volume.

Volume creation is need to be performed only on one of the virtual machine/node in the cluster.

Add the disk into failover cluster

Open failover cluster manager on the node where the volume is created --> failover cluster name --> storage --> disks --. add disk --> select the shared disk from the list.

Now login to the 2nd virtual machine/node --> open failover cluster manager --> cluster name --> storage --> disks

You could see the shared volume is added into the cluster disks

In-order to use the disk as a shared one, convert it into cluster shared volume (CSVFS)

On failover cluster manager window --> storage --> disks --> Add to cluster shared volume from the right side menu pane

Now the attached disk is added into failover cluster and converted into cluster volume. it is ready to use.

To test the shared volume, login to the 1st virtual machine "fsclusternode01" --> open file explorer --> navigate to C:\Windows\ClusterStorage\volume1 and create a folder and file

Now login to the another node/VM and check the same folder & file exists under C:\Windows\ClusterStorage\volume1.

If You check the properties of shared disk from Disks --> your shared disk name --> overview

I've also tried to create snapshot of shared disk and created a new disk from it, so the shared disk in can be administer in the same way as normal managed disk in azure with a additional feature of sharing.

Size and performance of the shared disk can be expanded but you need to stop the virtual machine before making the change.

Supported use cases of Azure shared disk

Some popular applications running on WSFC include:

Create an FCI with Azure shared disks (SQL Server on Azure VMs)
Scale-out File Server (SoFS) [template] (https://aka.ms/azure-shared-disk-sofs-template)
SAP ASCS/SCS [template] (https://aka.ms/azure-shared-disk-sapacs-template)
File Server for General Use (IW workload)
Remote Desktop Server User Profile Disk (RDS UPD)

Linux

Azure shared disks are supported on:

If you would like to explore more feel free to have a look into the below Microsoft documentation.

https://docs.microsoft.com/en-us/azure/virtual-machines/disks-shared

Thanks for reading and hope this helps.

Happy to help 😊 if you have any queries, feel free to put your queries into the comment box

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Sunday, February 21, 2021

Azure Managed Shared Disk