ZRS disk replication through ASR into region that does not support availability zones

Hello Tristan Kosciuch,

Thanks for posting your query in Microsoft Q&A portal

Azure Site Recovery (ASR) does not support replicating ZRS (Zone-Redundant Storage) disks to a target region that does not support availability zones, where only LRS (Locally Redundant Storage) is available. This is because ZRS replication inherently depends on zone availability in the region. ASR enforces target disk types that match supported replication scenarios for regional disaster recovery, ZRS must replicate to ZRS, for zonal disaster recovery, LRS can replicate to LRS.

Since your disaster recovery (DR) region does not support availability zones, ASR only allows replication targets that match the source disk's redundancy options in your case, ZRS to ZRS. The Azure portal only shows standard and premium ZRS as replication target options for ZRS disks, not LRS, this explains why you cannot select LRS for the target disks.

To resolve this,

• Change the source disks on your FCI cluster from ZRS to LRS if you want to replicate to a DR region that only supports LRS.

Note that changing disk redundancy can imply disk recreation or data migration steps.

Azure Site Recovery does not convert between ZRS and LRS redundancy types during replication; the disk types must be compatible with the source and target regions' zone support.

Refer documents for more details:

• https://learn.microsoft.com/en-us/azure/site-recovery/shared-disk-support-matrix
• https://learn.microsoft.com/en-us/azure/site-recovery/azure-to-azure-how-to-enable-replication
• https://learn.microsoft.com/en-us/azure/storage/common/redundancy-migration?tabs=portal#change-the-redundancy-configuration-using-azure-portal-powershell-or-azure-cli

I hope the provided answer is helpful, do let me know if you have any further questions on this Please accept as Yes if the answer is helpful so that it can help others in the community.

When using Azure Site Recovery (ASR) with ZRS disks, it's important to note that ZRS is only supported in regions that have availability zones. If your disaster recovery (DR) target region does not support availability zones, you will not be able to use ZRS disks for replication in that region. This is likely the reason you are encountering the error when trying to enable ASR for your FCI cluster VMs.

To resolve this issue, you would need to consider changing the redundancy option for your disks to LRS (Locally Redundant Storage), which is supported in all Azure regions, including those without availability zones. However, since you mentioned that the portal does not allow you to select LRS as a target, it may be necessary to first detach the ZRS disks from the VMs and then reconfigure them as LRS disks before attempting to enable ASR again.

Make sure to check the limitations and requirements for using ASR with different types of disks in Azure to ensure compatibility with your setup.