Customers hosting VMs in Azure may experience an error when attempting to create a large machine catalog or add additional machines in bulk, resulting in failure to create new machines.  This error will appear in Azure as:

"Too many attempts to copy from a writable resource (a managed disk); please use a snapshot source to create many copies in a short time."

• Up-to 49 disks can be created concurrently.  For now, Azure suggests that customers use shared image gallery as the source for deployments at scale.

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Problem Cause

OS disks of Trusted VMs have an accompanying storage object for the TPM state of the VM. Some of the Azure scalability enhancements, for creating number of OS disks from a Snapshot in quick succession, haven’t been implemented for the TPM state of Trusted VM OS disks.  Azure has identified repair items based on how they handle Non-TVM disk creation at scale and extend same optimizations to TVM disks to offer greater concurrent limits.

Large MCS deployments in Azure may fail due to Azure throttling of disk clones. "Too many attempts to copy from a writable resource (a managed disk); please use a snapshot source to create many copies in a short time."