Citrix recently announced preview support for Azure Managed Disks in Citrix Cloud’s XenApp and XenDesktop service. Today, we are pleased to announce the release of the production version. Managed Disks provides scalable and highly available storage without the need to create storage accounts and worry about IOPS constraints. Complementing the availability of Managed Disks are two new master image options: Managed Disks and Managed Snapshots.
Overview of Managed Disks
Azure Managed Disks is an elastic disk storage system that is offered as an alternative to the current storage account-based system. Currently, XenDesktop must create and manage multiple IOPS-constrained storage accounts to provide storage for the VHD blobs that hold the operating system and data disks for provisioned virtual machines (VDAs). In addition, copying images between storage accounts is slow, so copying each OS disk directly from the master image is not feasible for catalogs that use multiple storage accounts. Instead, the master image is replicated to each storage account when a catalog is created and updated so that each OS disk can be copied from a copy of the master image in the same storage account.
Managed Disks eliminates the complexity of storage accounts and offers a simple scalable and highly available solution for creating and managing disks and does away with the time-consuming need to replicate master images to storage accounts. Furthermore, machine reliability is improved as Managed Disks are allocated to storage clusters in a manner that optimizes the distribution across fault domains.
An Azure resource group can hold no more than 800 Managed Disks. By default, XenDesktop provision three disks per machine: OS Disk, Identity Disk and Write Back Cache Disk. XenDesktop will provision no more than 240 machines per resource group leaving a small buffer for future use up to the theoretical 266 machines per resource group. Catalogs with more than 240 machines will therefore span multiple resource groups.
The billing policy for Managed Disks is currently different from unmanaged disks (VHDs in storage accounts), so there is a small difference in cost. Azure also has some Managed Disks specific limitations which are documented further down in this article.
More details about Azure Managed Disks support in Citrix Cloud can be read in the following article: https://www.citrix.com/blogs/2018/02/21/support-for-azure-managed-disks-goes-into-production/