Merge pull request #307380 from mmkiran21-git/azure-vm-backup-faq

Addressed EEE 33040776, 35038483, 35078711, 35018239, 26856548, 27315261, 27460234, 33578774

Author: prmerger-automator[bot]

articles/backup/backup-azure-vm-backup-faq.yml

@@ -4,7 +4,7 @@ metadata:
   description: In this article, discover answers to common questions about backing up Azure VMs with the Azure Backup service.
   ms.topic: faq
   ms.service: azure-backup
-  ms.date: 06/23/2025
+  ms.date: 10/29/2025
   author: AbhishekMallick-MS
   ms.author: v-mallicka
   ms.custom: build-2025
@@ -151,7 +151,7 @@ sections:
 
       - question: In Azure VM Backup, what is the Snapshot Tier and Storage Redundancy for snapshot taken as part of backup?
         answer: |
-          In Azure VM Backup, snapshots are taken using the Standard HDD tier type, regardless of the source VM disk tier. By default, the storage redundancy for these snapshots is Locally Redundant Storage (LRS). However, if the VM backups are managed by an Enhanced Policy and the underlying source disk storage supports Zone Redundant Storage (ZRS), the snapshots will be of the ZRS type.
+          In Azure VM Backup, snapshots are taken using the Standard HDD tier type, regardless of the source VM disk tier. By default, the storage redundancy for these snapshots is Locally Redundant Storage (LRS). However, if the VM backups are managed by an Enhanced Policy and the underlying source disk storage locates in the region which supports Zone Redundancy, snapshots will be of Zone Redundant Storage.
 
       - question: How long can I retain backup points of Azure VMs using the backup policy?
         answer: |
@@ -162,12 +162,38 @@ sections:
           - **Retention of monthly backup points**: 1188 months
           - **Retention of yearly backup points**: 99 years 
 
-      - question: Can I back up a VM disks that're created in the Azure Classic Storage?
+      - question: Can I back up a VM disks that are created in the Azure Classic Storage?
         answer: |
-          No, the support for disks created in Azure Classic Storage is no longer available. To ensure continued functionality, you must migrate these disks to Azure Resource Manager (ARM) Storage. Also, Classic Storage accounts can't support ARM-based Virtual Machines (VMs), and no workarounds exist to enable compatibility.
+          No, the support for disks created in Azure Classic Storage is no longer available. To ensure continued functionality, you must migrate these disks to Azure Resource Manager Storage. Also, Classic Storage accounts can't support ARM-based Virtual Machines (VMs), and no workarounds exist to enable compatibility.
 
           >[!Important]
-          >Support for backup of all Classic VMs is planned for deprecation on September 30, 2025. We recommend that you migrate the Classic VMs and associated disks to ARM Storage before this timeline to avoid disruptions.
+          >Support for backup of all Classic VMs is planned for deprecation on September 30, 2025. We recommend that you migrate the Classic VMs and associated disks to Azure Resource Manager Storage before this timeline to avoid disruptions.
+ 
+      - question: How Soft-Delete behavior occurs when the retention of the backup policy is changed or modified?
+        answer: |
+          When the retention period of a backup policy is changed, the soft-delete behavior for restore points (RPs) is determined based on the current policy at the time of evaluation—not the policy in place when the RP was created.
+      - question: I have an Azure VM stored in a zone with a Premium SSD ZRS disk. What happens if I restore this VM to a Paired region using CRR where ZRS is not supported?
+        answer: |
+          When restoring a VM to a peered region that does not support Zone-Redundant Storage (ZRS), Azure Backup will automatically create the disk in the same performance tier (e.g., Standard or Premium) as the original disk, but with Locally Redundant Storage (LRS) instead of ZRS. This ensures that the restore operation completes successfully, even though the redundancy model changes.
+      - question: Is 64 TB disk support for Azure Backup available in all regions?
+        answer: |
+          Azure Backup supports individual disk sizes up to 64 TB and a combined total of 512 TB per VM. However, this capability is region dependent. While initially available in select regions, support has expanded to additional locations. Customers are advised to check the latest regional availability or consult Azure Support to confirm support in their target region.
+      - question: How does the MDCC backup works via Enhanced Policy with and without selecting the option "only Crash Consistency Snapshot"?
+        answer: |
+          The behavior of MDCC backup under Enhanced Policy depends on whether the **"Only Crash Consistency Snapshot"** checkbox is selected:
+          
+          **When the checkbox is NOT selected:**
+          
+          Enhanced Policy will attempt to take application-consistent or filesystem-consistent backups. However, if these attempts fail, the policy will fall back to crash-consistent backups at specific intervals:
+            - A crash-consistent snapshot will be taken on the 4th, 6th, and 8th attempt.
+            - This fallback ensures backup continuity even when consistency cannot be guaranteed.
+          
+          **When the checkbox is selected:**
+
+          The policy will not attempt application or filesystem consistency. Instead, it will directly initiate a crash-consistent MDCC backup without any retries for higher consistency levels.
+          
+          This option is useful when speed and simplicity are prioritized over consistency guarantees.
+
   - name: Restore
     questions:
       - question: How do I decide whether to restore disks only or a full VM?
@@ -239,7 +265,7 @@ sections:
 
       - question: Is there a limit to trigger restore in a day?
         answer: |
-          The restore limit applies per data source within a 24-hour window. You can restore the same VM up to 20 times in that period. Restoring multiple VMs simultaneously is allowed, but may trigger throttling from other Azure services, such as [Azure Resource Manager (ARM) due to request limits](/azure/azure-resource-manager/management/request-limits-and-throttling#migrating-to-regional-throttling-and-token-bucket-algorithm).
+          The restore limit applies per data source within a 24-hour window. You can restore the same VM up to 20 times in that period. Restoring multiple VMs simultaneously is allowed, but may trigger throttling from other Azure services, such as [Azure Resource Manager due to request limits](/azure/azure-resource-manager/management/request-limits-and-throttling#migrating-to-regional-throttling-and-token-bucket-algorithm).
 
       - question: How does restored disk SKU depend on target SA provided?
         answer: |
@@ -318,6 +344,12 @@ sections:
           - **MarketPlace Image VMs**: Only VMs created from a MarketPlace image will have the Offer, SKU, and Publisher details. These properties are derived from the VM image itself. When a VM is created from a MarketPlace image, the createOption is set to **from image**. This ensures that the Offer, SKU, and Publisher properties are included during the VM creation process. 
           - **VMs Created from Disks**: When a VM is created from disks (such as restored VMs, uploaded VMs, or VMs created from snapshots), the createOption is set to **Attach** instead of "from image". In this case, the Offer, SKU, and Publisher properties are not included because these properties are read-only and can only be added during the initial VM creation process when the createOption is **from image**. 
 
+      - question: What is the expected throughput when we perform the restore from the Vault storage.
+        answer: |
+          For Tier-2 restores (restores from vault data), the time required depends on the amount of allocated data that needs to be transferred. In one observed case, disks with approximately 2 TB of allocated data each contributed significantly to the overall transfer time. While a transfer rate of 30 MBps is generally considered optimal, we achieved around 50 MBps in this instance.
+          
+          For example, if a customer has a 16 TB disk with 2 TB of allocated data per segment, the total restore time could extend up to 20 hours at the optimal transfer rate.
+ 
   - name: Manage VM backups
     questions:
       - question: What happens if I modify a backup policy?
@@ -470,3 +502,12 @@ sections:
 
           >[!Note]
           >GRS functions only when both paired regions support SSD V2/Ultra disks. 
+
+      - question: Why don’t I see the updated expiry time for my Recovery Points immediately after changing the backup policy?
+        answer: |
+          When you modify a backup policy (for example, changing the retention duration), the updated expiry time for Recovery Points (RPs) is not reflected instantly on the Azure portal. This is expected behavior.
+          
+          The expiry time is updated only after the system runs its daily cleanup process (also known as the expired Recovery Points pruning job). This job typically runs once every 24 hours. Therefore, it may take up to 24 hours for the new expiry time to appear on the portal for existing or newly created Recovery Points.
+          
+          If you don’t see the updated expiry time immediately, please wait for up to 24 hours before raising a support request.
+