Azure Managed Disk
Does ZopNight manage Azure Managed Disk?
Azure managed disks bill for provisioned capacity, not data written. A 1 TB premium SSD costs the same at 5 percent full as at 95 percent, and keeps billing while its VM is deallocated or deleted. ZopNight discovers every disk with attachment state via Resource Graph and flags unattached disks and premium-to-standard downgrades.
Rules that fire on Azure Managed Disk
At a glance
| Field | Value |
|---|---|
| Scheduling notes | discovery and cost visibility only. |
Managed disks provide block storage for Azure VMs, billed for provisioned capacity whether attached or not. Unattached disks left behind by deleted VMs are one of the most reliable sources of pure waste.
Billed on what you provisioned, not what you wrote
A managed disk bills by SKU and provisioned size, not by data stored. Premium SSDs bill in fixed size tiers, so a disk provisioned just past a tier boundary pays the full next tier. The meter also has no relationship with the VM’s power state: disks bill at their full rate while the VM is deallocated, and keep billing after the VM is deleted unless they are explicitly deleted too. This is why a fleet that schedules its VMs diligently can still carry a large, flat storage line.
Discovery and the signals ZopNight attaches
Discovered via Azure Resource Graph with attachment state, SKU, and size. Recommendations flag unattached disks and Premium-to-Standard SSD downgrades, and Cost Management billing attributes spend. Disk latency and queue metrics are derived via the attached VM using the LUN dimension, and ML auto-tagging covers this type. A disk has no stop operation, so it is not schedulable. ZopNight’s leverage here is detection and rightsizing, and disk cost is factored into VM scheduling savings estimates so the projected saving from deallocating a VM never overstates what deallocation delivers.
Three classic disk leaks
Orphaned disks: deleting a VM does not delete its data disks by default, and the disks bill on quietly for months. Premium where standard would do: dev and test machines on premium SSD pay a multiple of standard SSD for IOPS nobody needs. Oversized provisioning: a disk sized generously on day one can never bill less, because Azure disks cannot be shrunk, only recreated smaller.
Auditing disks in the portal
Azure portal → Disks lists every managed disk in the subscription with an Owner (attached VM) column. Filter the Disk state column to Unattached for the fastest single audit in Azure. Every row on that filtered list is billing for nothing.