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Azure Ephemeral OS Disks: What Are They and How Do They Benefit MSPs?

Virtual Machines in Azure run on top of the Microsoft Hyper-V hypervisor on physical hardware inside Azure data centers around the world.  Each VM can be attached to two types of storage: Local and Remote

Local VM Storage 

This type is non-persistent (i.e. volatile) storage that is internal to the physical Hyper-V host that a VM is running on at any given time.  As soon as the VM is moved to another physical host as a result of a deallocate (stop) and start command, hardware or VM crash, or Azure fabric maintenance, the local storage is wiped clean and any data stored on it is lost.  Because of the volatile nature of local storage, no important data can be stored on it.  However, it is ideal for non-persistent data such as temp files and page/swap files.  Local storage is typically visible as the D: drive on Windows VMs in Azure and has a text file in the root directory warning users against data loss. 

Remote VM Storage 

This storage type is persistent and comes in the form of managed (or unmanaged) disks.  These disks can have different performance and redundancy characteristics. 

For more information about Azure storage for MSPs, see Microsoft Azure Fundamentals: Terminology, Hierarchy, and Resources. 

Remote storage is required for any VM’s OS disk (i.e. C: drive where Windows is installed) and certainly for any data disks that are intended to permanently store important data.  In order to retain the data and persist across moves of the VM from one physical host to another, the remote storage is, well… remote from the VM itself.  It is stored on Azure’s storage system and VMs attach to it via the network.  The physical Hyper-V host running the VM is independent of the remote storage system, which means that any Hyper-V host or VM can mount a remotely stored disk. 

Remote storage has the critical advantage of being persistent, while local storage has the advantage of being faster (because it’s local to the VM – on the same physical host) and it is free.  When starting an Azure VM, you only pay for its OS and data disks that are remote.  Local storage on a VM (i.e. D: drive) is included in the price of the VM itself and carries no usage charge of its own. 

Ephemeral OS Disks

Recently, Microsoft introduced the concept of Ephemeral OS disk for certain types of VMs.  An Ephemeral OS disk is stored on local storage and is therefore faster and free, but it is not persistent.  It is therefore only used in situations where the VM is based on an image and every time it is started the OS disk will get “regenerated” from the generalized image and any changes made to the OS disk (C:) will be lost if the VM moves to another host or is reallocated.   

Why does this matter?  OS disks on Windows VMs, such as RDS or AVD session hosts, constitute a significant cost component ($20 or so for a 128GB Premium SSD P10 disk).  Using generalized RDS/AVD host images and Ephemeral OS disks removes this cost component completely, further reducing the cost of running virtual desktops in Azure. 

The performance of Ephemeral OS disks is also significantly better than remote storage OS disks.  This is because they are stored on local SSD storage and don’t have to be mounted over the network in Azure.  This increased speed and reduced latency leads to faster VM start/stop operations, faster provisioning, and overall increased performance.  How much faster are they?  Micha Wets wrote a great article comparing the performance of AVD hosts using Ephemeral OS disks and remote OS disks.  Take a look to see how much of a difference this makes. 

How can you take advantage of Ephemeral OS disks?  

Since these OS disks make the most sense with VMs based on generalized images, and because Nerdio’s implementation of AVD host pools is based on Azure VM Scale Sets that use an image natively, this is going to be a very easy feature to enable when creating new AVD host pools in the future.  You will be able to check a box to select the use of Ephemeral OS disks instead of traditional managed disks when creating a new AVD host pool in the Nerdio Admin Portal on the Servers screen. 

The result will be faster disk performance of AVD virtual desktops and significant cost savings resulting from eliminating the need to pay for traditional, remote storage-based managed disks.   

At Nerdio, we strive to stay on the leading edge of newly released Azure features and integrate them into our product to improve our MSP partners’ margins and experience.  We’re always on the lookout for better, more efficient ways to empower MSPs to build successful cloud practices in Microsoft Azure. 


Multi-Cloud and On-Premises Deployment with Azure Stack HCI (Coming Soon)

Deploy Azure Virtual Desktop in Azure and extend the session host VM placement to on-premises and other cloud using Azure Stack HCI. Nerdio Manager automates deployment of session hosts, AVD agent installation, and full integration into the AVD deployment in Azure.

Create a brand new Azure Virtual Desktop environment or allow Nerdio Manager to discover an existing deployment, connecting to existing resources, and manage them.

Deploy Nerdio Manager from Azure Marketplace and configure a new AVD environment with an easy to follow, step-by-step configuration wizard. First group of users can access their AVD desktop in less than 2 hours.

Service providers, system integrators, and consultants can leverage Nerdio Manager’s scripted AVD deployment template. Create complete environments with desktop images, host pools, and auto-scaling in minutes.

Create and manage AVD environments that span Azure regions and subscriptions. Quickly link Vnets and resource groups and manage AVD deployments world-wide from unified portal.

Link multiple Azure tenants under the same Nerdio Manager instance and manage AVD deployments that span Azure AD tenants. User identities and session host VMs can run in separate tenants for maximum flexibilty and security.

Deploy and manage AVD environments that span across sovereign Azure Clouds. Cross-sovereign cloud support allows identity (e.g. users and groups) to be in one Azure Cloud, while session host VMs are in another Azure Cloud.

Management of workspaces, host pools, app groups, RemoteApps & custom RDP settings

Administer every aspect of AVD with Nerdio Manager including workspaces, host pools, application groups, RemoteApp publishing, RDP properties, session time limits, FSLogix, and much, much more. Every Azure service that AVD relies on can be managed with Nerdio Manager.

Deploy and manage AVD session host VMs. Hosts can be created manually or with auto-scaling, deleted on-demand or on a schedule, re-imaged to apply updates, run a scripted action, resized, put into or taken out of drain mode, and more.

Manage user sessions across the entire AVD environment, within a workspace, host pool or on a single host. Monitor session status, disconnect or log off the user, shadow or remote control to provide support, or send user an on-screen message.

End users have the ability to log into Nerdio Manager with their Azure AD credentials and manage their own session, restart their desktop VM, or start a session host if none are started in a host pool. (Ability to resize and re-image own desktop is coming soon.)

Create, link, and manage Azure Files shares including AD domain join. Synchronize Azure Files permissions with host pools, configure quotas, and enable SMB multi-channel. Manage file lock handles and configure Azure Files auto-scaling to increase quota as needed.

Create, link, and manage Azure NetApp Files accounts, capacity pools and volumes. Configure provisioned volume size, monitor usage, and use auto-scaling to automatically adjust volume and capacity pool size to accommodate the needed capacity and latency requirements.

FSLogix configuration can be complex and overwheling, but not with Nerdio Manager. Create one or more FSLogix profiles with all the needed options, point at one or more Azure Files, Azure NetApp Files, or server locations and select from VHDLocations, CloudCache and Azure Blob storage modes.

Multiple identity source profiles can be set up and used automatically on different host pools. Active Directory, Azure AD DS, and Native Azure AD are all supported. Choose the appropriate directory profile when adding a host pool and all VMs will automatically join this directory when being created.

Create a copy of a host pool with all of its settings: auto-scale config, app groups and RemoteApps, MSIX AppAttach, user/group assignments, VM deployment settings, etc. Save time by creating host pool “templates” that can be cloned to any Workspace, Azure region or subscription instead of starting from scratch.

Apply user session time limits at host pool level. Automatically log off disconnected sessions, limit the duration of idle sessions, control empty RemoteApp session behavior and more.

Assign Azure AD users to personal desktops to ensure the user will log into a pre-configured VM. Un-assign personal desktops from users who leave the organization and re-use these VMs for new users.

Pre-configure custom Azure tags for all Azure resources associated with each host pool. Tags can be used for charge-back and cost allocation by host pool.

When creating session hosts using NV-series VMs NVIDIA and AMD GPU drivers are automatically installed.

Move existing host pools from Fall 2019 (Classic) object model to Spring 2020 (ARM) object model. Choose to whether to move or copy user assignments. Existing session hosts are automatically migrated or new ones can be created in the ARM host pool.

Automatically enable and configure AVD integration with Azure monitor. Zero configuration required. Azure Monitor Insights for AVD can be used instead of or in conjunction with Sepago Monitor.

AVD personal desktops to Windows 365 Cloud PC migration (Coming Soon)

Migrate users from AVD personal desktops to Windows 365 Enterprise Cloud PCs using an existing image and user assignment. (Coming soon)


Cloud PC License Usage Optimization (Coming Soon)

Cloud PC device lifecycle management

Cloud PC user group assignment

Intune primary user management on Cloud PCs

Migrate AVD personal desktops to Cloud PCs (Coming Soon)

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