Backup policy modification

Question

Backup policy modification

Davidmiller Miller 65

How to modify back up policy of a VM, Please let me know the steps.

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Answer accepted by question author

Suchitra Suregaunkar 15,385 Microsoft External Staff Moderator

Hello Davidmiller Miller

Thank you for posting your query on Microsoft Q&A platform.

There are two distinct scenarios here, so let me cover both clearly to avoid any confusion:

Modify the settings of an existing backup policy (e.g., change frequency or retention on DefaultPolicy) this affects every VM associated with that policy.
Switch a VM from one backup policy to another (e.g., move VM1 from DefaultPolicy to CustomPolicy-Gold) this affects only that specific VM.

Scenario 1: Modify an Existing Backup Policy using Azure Portal.

Sign in to the Azure Portal → search for Backup center (or open the Recovery Services vault directly).
In the vault, go to Backup policies under the Manage section.
Click the policy you want to modify (e.g., DefaultPolicy).
Adjust the required settings:
- Backup frequency (Daily / Weekly / Hourly for Enhanced policies)
- Retention range (daily, weekly, monthly, yearly)
- Instant Restore snapshot retention (1–5 days for Standard; 1–30 days for Enhanced)
- Time zone
Click Save. The change automatically applies to all VMs associated with this policy.

You cannot change a policy type from Standard → Enhanced by editing, you must migrate. Also, the Standard policy doesn't support newer offerings like Ultra Disk and Premium SSD v2.

Option 2: Azure CLI (export → edit JSON → apply)

This is the documented method per Microsoft Learn for VM policies. [learn.microsoft.com]

Step 1 — Export the current policy to JSON:

az backup policy show </span>
 --name testing123 </span>
 --resource-group rg1234 </span>
 --vault-name testvault > Policy.json

Step 2 — Edit Policy.json and update the parameter you need. For example, to change weekly retention to 60 weeks:

"retentionDuration": {
 "count": 60,
 "durationType": "Weeks"
}
`

Step 3 — Apply the updated policy:

az backup policy set </span>
 --resource-group rg1234 </span>
 --vault-name testvault </span>
 --policy C:\temp2\Policy.json </span>
 --name testing123

Step 4 — Validate by running az backup policy show again, or check in the portal.

You can grab a sample policy JSON template with az backup policy get-default-for-vm

Scenario 2: Change Which Backup Policy a VM Uses

This is the more common ask when a VM is already protected and you simply want it to follow a different policy.

Option 1: Azure Portal

Open the Recovery Services vault that protects the VM.
Go to Backup items → Azure Virtual Machine → select the VM.
On the VM's backup details page, click the current Backup policy name.
The Change backup policy blade opens — select the new policy from the dropdown.
Click Save. The VM immediately starts honoring the new policy — no need to stop backup or lose recovery points.

Option 2: PowerShell

$vault = Get-AzRecoveryServicesVault -ResourceGroupName "<RG>" -Name "<VaultName>"

$TargetPol = Get-AzRecoveryServicesBackupProtectionPolicy `
    -Name "<NewPolicyName>" -VaultId $vault.ID

$BkpItem = Get-AzRecoveryServicesBackupItem `
    -WorkloadType AzureVM -BackupManagementType AzureVM `
    -Name "<VMName>" -VaultId $vault.ID

Enable-AzRecoveryServicesBackupProtection `
    -Item $BkpItem -Policy $TargetPol -VaultId $vault.ID

This reuses the existing protected item and just re-points it to the new policy existing recovery points are preserved.

Best Practices to Keep in Mind:

Tier your policies by workload criticality (mission-critical → multiple daily backups + long retention, non-critical → daily/weekly with shorter retention).
Enable Soft Delete / Immutable Vault for ransomware protection before relaxing any retention.
There's a rate limit when modifying policies via ARM/PowerShell/CLI max 50 policy create/edit operations per 24 hours per vault.
Test a restore after any retention or frequency change to confirm RPO/RTO expectations are met.

Thanks,
Suchitra.

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1 additional answer

Your answer

Answer 1

To modify the backup policy of an Azure VM, use either the Azure portal or Azure CLI, depending on what needs to be changed.

Modify an existing backup policy (Azure portal)

This changes the policy itself (schedule, retention, etc.) and affects all VMs using that policy.

Sign in to the Azure portal and open the Recovery Services vault.
Under Manage, select Backup policies.
Select the backup policy with type Azure Virtual Machine.
Select Modify.
Change the required settings (for example, backup schedule or retention).
Save the changes.

All VMs associated with this policy will use the updated settings.

Switch the backup policy for a specific VM (Azure portal)

This keeps policies as they are but moves a VM from one policy to another.

In the Recovery Services vault, on the Backup Items tile, select Azure Virtual Machine.
In Backup Items (Azure Virtual Machine), select the VM whose policy needs to be changed.
On the VM’s backup item blade, select the current backup policy.
Choose a different backup policy from the list (or create a new one if needed).
Select Save. The new policy is applied immediately to that VM.

Modify an existing VM backup policy using Azure CLI

This edits the JSON definition of the policy and reapplies it.

Export the current policy to JSON:

   az backup policy show \
     --name <PolicyName> \
     --resource-group <ResourceGroupName> \
     --vault-name <VaultName> > Policy.json

Open Policy.json and edit the required fields. For example, to change weekly retention to 60 weeks, update:
```
   "retentionDuration": {
     "count": 60,
     "durationType": "Weeks"
   }
```
Save the JSON file.

Apply the updated policy:

   az backup policy set \
     --resource-group <ResourceGroupName> \
     --vault-name <VaultName> \
     --policy /full/path/to/Policy.json \
     --name <PolicyName>

Enhanced policy (CLI-specific note)

If the VM uses an Enhanced policy, include the subtype when creating or updating:

Create Enhanced policy:

  az backup policy create \
    --policy @Policy.json \
    --resource-group <ResourceGroupName> \
    --vault-name <VaultName> \
    --name <PolicyName> \
    --backup-management-type AzureIaaSVM \
    --PolicySubType Enhanced

Update Enhanced policy:

  az backup policy set \
    --policy @Policy.json \
    --resource-group <ResourceGroupName> \
    --vault-name <VaultName> \
    --PolicySubType Enhanced

References: