Update azure-to-azure-support-matrix.md

Updating ASR docs about UAMI.

Author: swapnilbel

articles/site-recovery/azure-to-azure-support-matrix.md

@@ -64,7 +64,7 @@ General purpose V2 storage accounts (Hot and Cool tier) | Supported | Usage of G
 Premium storage | Supported | Use Premium Block Blob storage accounts to get High Churn support. For more information, see [Azure VM Disaster Recovery - High Churn Support](./concepts-azure-to-azure-high-churn-support.md).
 Region |  Same region as virtual machine  | Cache storage account should be in the same region as the virtual machine being protected.
 Subscription  | Can be different from source virtual machines | Cache storage account must be in the same subscription as the source virtual machine(s). <br> To use cache storage from the target subscription, use PowerShell.
-Azure Storage firewalls for virtual networks  | Supported | If you're using firewall enabled cache storage account or target storage account, ensure you ['Allow trusted Microsoft services'](../storage/common/storage-network-security.md#exceptions).<br></br>Also, ensure that you allow access to at least one subnet of source Vnet.<br></br>Note: Don't restrict virtual network access to your storage accounts used for Site Recovery. You should allow access from 'All networks'.
+Azure Storage firewalls for virtual networks  | Supported | If you're using firewall enabled cache storage account or target storage account, ensure you ['Allow trusted Microsoft services'](../storage/common/storage-network-security.md#exceptions).<br></br>Also, ensure that you allow access to at least one subnet of source Vnet.<br></br>Note: If you are using User Assigned Managed Identity (UAMI) created on recovery services vault, do not restrict virtual network access to your storage accounts used for Site Recovery. You should allow access from 'All networks' if you use vault UAMI.
 Soft delete | Not supported | Soft delete isn't supported because once it's enabled on cache storage account, it increases cost. Azure Site Recovery performs frequent creates/deletes of log files while replicating causing costs to increase.
 Encryption at rest (CMK) | Supported | Storage account encryption can be configured with customer managed keys (CMK)
 Managed identity | Not supported | The cached storage account must allow shared key access and Shared Access Signatures (SAS) signed by the shared key. Recent changes in Azure Policy disable key authentication due to security concerns. However, for Site Recovery, you need to enable it again.