# Restore the prior quantity when a capacity-reservation increase fails

> What state should an operator restore after Azure cannot satisfy an increase to an existing capacity reservation?

- Canonical URL: https://update.dsesecurity.com/updates/dse-20260909-033-restore-the-prior-quantity-when-a-capacity-reservation-increase-fails/
- Publisher: Detection Systems & Engineering (DSE Security)
- Author: DSE Security Editorial Team
- Published: 2026-09-10T00:31:23+00:00
- Modified: 2026-09-10T00:32:00+00:00
- Last reviewed by DSE: 2026-09-09
- Resource type: Playbook
- DSE priority: Information
- Topics: Business Continuity, IT
- Reading time: 2 minutes

## What you need to know

What state should an operator restore after Azure cannot satisfy an increase to an existing capacity reservation?

## Potentially affected

Operators changing the quantity of an existing Azure capacity reservation.

## DSE recommendation

Preserve the last successfully reserved quantity and use it as the explicit recovery target for an unsuccessful increase.

## Article

## Source facts

Microsoft warns that an unsuccessful request for more reserved capacity can rarely leave an existing reservation in Failed state and unavailable until its previous quantity is restored. VMs already associated with that failed reservation continue operating normally. The documented recovery can obtain the successfully reserved amount from currentCapacity in the reservation’s instance view and update the requested quantity accordingly. [Microsoft Learn](https://learn.microsoft.com/en-us/azure/virtual-machines/capacity-reservation-modify).

## Applicability

Use this response for a quantity increase on an existing reservation, not as a general remedy for every VM allocation error. Record the intended increase, previous successful amount, reservation identifier, and returned failure. Separate the reservation’s provisioning state from observations of its associated workloads.

## DSE recommendation

Preserve the last successfully reserved quantity and use it as the explicit recovery target for an unsuccessful increase. Ask the capacity owner to approve restoring that amount before retrying a larger request. Keep the requested quantity, observed current capacity, and resulting state in one record. Assign any remaining growth requirement its own follow-up instead of interpreting restoration as delivery of the extra capacity.

## Verification

After the approved correction, inspect the reservation’s quantity and state again. Compare the restored value with the preserved successful amount and reconcile the list of associated VMs. Have the workload owner check the relevant service separately, particularly if other changes occurred during the incident. Close the recovery only when the reservation-state discrepancy is resolved, and leave the unmet expansion request visible to its owner.

## Official references

[Microsoft Learn: Modify a capacity reservation in Azure](https://learn.microsoft.com/en-us/azure/virtual-machines/capacity-reservation-modify). Source reviewed September 9, 2026.

## Primary reference

- Name: Modify a capacity reservation in Azure - Azure Virtual Machines | Microsoft Learn
- Authority: Microsoft Learn
- URL: https://learn.microsoft.com/en-us/azure/virtual-machines/capacity-reservation-modify
- Source publication date: Not stated by the source

## Citation and use

Preferred citation: “Restore the prior quantity when a capacity-reservation increase fails,” DSE Security, https://update.dsesecurity.com/updates/dse-20260909-033-restore-the-prior-quantity-when-a-capacity-reservation-increase-fails/
Publishing principles: https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/
Usage and citation policy: https://update.dsesecurity.com/usage/
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