Merge pull request #276953 from rajats22/aksbackupupdate-0306-01

Disk Backup Documentation Updates

Author: v-dirichards

articles/backup/azure-kubernetes-service-cluster-backup-support-matrix.md

@@ -61,6 +61,8 @@ You can use [Azure Backup](./backup-overview.md) to help protect Azure Kubernete
 
 - For successful backup and restore operations, the Backup vault's managed identity requires role assignments. If you don't have the required permissions, permission problems might happen during backup configuration or restore operations soon after you assign roles because the role assignments take a few minutes to take effect. [Learn about role definitions](azure-kubernetes-service-cluster-backup-concept.md#required-roles-and-permissions).
 
+- Backup vault does not support Azure Lighthouse. Thus, cross tenant management cannot be enabled by Lighthouse for Azure Backup for AKS and you cannot backup/restore AKS Clusters across tenant.
+
 - Here are the AKS backup limits:
 
   | Setting | Limit |

articles/backup/backup-managed-disks.md

@@ -70,10 +70,12 @@ A Backup vault is a storage entity in Azure that holds backup data for various n
 
    You can pick **first successful backup** taken daily or weekly, and provide the retention duration that the specific backups are to be retained before they're deleted. This option is useful to retain specific backups of the day or week for a longer duration of time. All other frequent backups can be retained for a shorter duration.
 
-   ![Retention settings](./media/backup-managed-disks/retention-settings.png)
+   ![Retention settings](./media/backup-managed-disks/retention-settings.png) 
 
    >[!NOTE]
-   >Azure Backup for Managed Disks uses incremental snapshots which are limited to 500 snapshots per disk. To allow you to take on-demand backups aside from scheduled backups, backup policy limits the total backups to 450. Learn more about [incremental snapshots](../virtual-machines/disks-incremental-snapshots.md#restrictions) for managed disk.
+   >Azure Backup for Managed Disks uses incremental snapshots which are limited to 500 snapshots per disk. At a point in time you can have 500 snapshots for a disk. Thus, to prevent backup failure the retention duration is limited by the snapshot limit. To allow you to take on-demand backups aside from scheduled backups, backup policy limits the total backups to 450. Learn more about [incremental snapshots](../virtual-machines/disks-incremental-snapshots.md#restrictions) for managed disk.
+
+   You can either set a maximum retention limit of 1 year or 450 disk snapshots, whichever reaches first. For example, if you have opted for a backup frequency of 12 hours, then you can retain each recovery point for maximum 225 days as the snapshot limit will be breached beyond that. 
 
 1. Complete the backup policy creation by selecting **Review + create**.
 

articles/backup/disk-backup-faq.yml

@@ -46,7 +46,7 @@ sections:
       - question: |
           Why does backup policy limit the retention duration?
         answer: |
-          Azure Disk Backup uses incremental snapshots, which are limited to 500 snapshots per disk. To allow you to take on-demand backups aside from scheduled backups, backup policy limits the total backups to 450. Learn more about [incremental snapshots](../virtual-machines/disks-incremental-snapshots.md#restrictions) for managed disks.
+          Azure Disk Backup uses incremental snapshots, which are limited to 500 snapshots per disk. To allow you to take on-demand backups aside from scheduled backups, backup policy limits the total backups to 450. You can either set a maximum retention limit of 1 year or 450 disk snapshots, whichever reaches first. For example, if you have opted for a backup frequency of 12 hours, then you can retain each recovery point for maximum 225 days as the snapshot limit will be breached beyond that. Learn more about [incremental snapshots](../virtual-machines/disks-incremental-snapshots.md#restrictions) for managed disks.
           
       - question: |
           How does the hourly and daily backup frequency work in the backup policy?
@@ -93,6 +93,11 @@ sections:
         answer: |
           During a restore operation, you can choose the subscription and a resource group where you want to restore the disk to. Azure Backup will create new disks from the recovery point in the selected resource group. This is referred to as a target resource group. Note that the Backup vault's managed identity requires the role assignment on the target resource group to be able to perform restore operation successfully. For more information, see the [restore documentation](restore-managed-disks.md).
           
+      - question: |
+          What is the maximum delay I can expect in backup start time from the scheduled backup time for the Disk Backup?
+        answer: |
+          Scheduled Backups are performed within a 2-hour window from the time scheduled as per the backup policy. Thus, you can expect a maximum delay of 2 hours in backup start time from the scheduled backup time for the Disk Backup.
+          
       - question: |
           What are the permissions used by Azure Backup during backup and restore operation?
         answer: |

articles/backup/disk-backup-support-matrix.md

@@ -31,7 +31,9 @@ Azure Disk Backup is available in all public cloud and Sovereign cloud regions.
 
 - Currently, the Original-Location Recovery (OLR) option to restore by replacing existing source disks from where the backups were taken isn't supported. You can restore from recovery point to create a new disk either in the same resource group as that of the source disk from where the backups were taken or in any other resource group. This is known as Alternate-Location Recovery (ALR).
 
-- Azure Backup for Managed Disks uses incremental snapshots, which are limited to 500 snapshots per disk. To allow you to take on-demand backup aside from scheduled backups, Backup policy limits the total backups to 480. Learn more about [incremental snapshot](../virtual-machines/disks-incremental-snapshots.md#restrictions) for managed disks.
+- Azure Backup for Managed Disks uses incremental snapshots, which are limited to 500 snapshots per disk. To allow you to take on-demand backup aside from scheduled backups, Backup policy limits the total backups to 420. Learn more about [incremental snapshot](../virtual-machines/disks-incremental-snapshots.md#restrictions) for managed disks.
+
+- You can either set a maximum retention limit of 1 year or 450 disk snapshots, whichever reaches first. For example, if you have opted for a backup frequency of 12 hours, then you can retain each recovery point for maximum 225 days as the snapshot limit will be breached beyond that. 
 
 - Azure [subscription and service limits](../azure-resource-manager/management/azure-subscription-service-limits.md#virtual-machine-disk-limits) apply to the total number of disk snapshots per region per subscription.
 
@@ -59,6 +61,8 @@ Azure Disk Backup is available in all public cloud and Sovereign cloud regions.
 
 - You can stop backup and retain backup data. This allows you to *retain backup data* forever or as per the backup policy. You can also delete a backup instance, which stops the backup and deletes all backup data. 
 
+- Backup Vault does not support Azure Lighthouse. Thus, cross tenant management experiences cannot be enabled by Lighthouse for Azure Disk Backup and you cannot backup/restore Azure Disks across tenant.
+
 - Azure Disk Backup limits are:
 
     | Setting | Maximum limit |