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We are excited to introduce the preview of Zone Redundant Storage (ZRS) option for Azure managed disks! This capability provides synchronous replication of data across the three Zones in a region, enabling disks to tolerate Zonal failures which may occur due to natural disasters or hardware issues.  ZRS option is currently supported for Premium SSD and Standard SSD disks.


 


Use ZRS disks for legacy applications to achieve better availability


You can achieve high availability for your workloads using application-level replication across two zones, for example, SQL Always On. However, suppose you are using industry-specific proprietary software or legacy applications like older versions of SQL Server, which don’t support application-level synchronous replication; ZRS disks will provide improved availability via storage-level replication. For example, if a zone goes down due to natural disasters or hardware failures, ZRS disk will continue to be operational. If your virtual machine (VM) in the affected Zone becomes unavailable, you could use a virtual machine in another zone and attach the same ZRS disk.


 


Use ZRS with shared disks


You can also use the ZRS option for shared disks to provide improved availability for clustered or distributed applications like SQL FCI, SAP ASCS/SCS. You can attach a shared ZRS disk to primary and secondary VMs allocated on different zones to take advantage of both ZRS disks and Availability Zones for VMs for higher availability. In the event of a primary zone failure, you can quickly fail over to the secondary VM using SCSI persistent reservation.


 


Use ZRS disks to achieve zero RPO


For LRS disks, you can achieve better durability by taking frequent backups of your disks using ZRS snapshots. You can also enable cross-zone disaster recovery for LRS disks via Azure Site Recovery. However, these options do not provide zero Recovery Point Objective (RPO). If your application must meet zero RPO, then ZRS disks could be the solution.


 


Pricing and performance


You can find the price for Premium SSD and Standard SSD ZRS disks at the disks storage pricing page. The IOPS and bandwidth provided by ZRS disks is same as the corresponding LRS disks. For example, a P30 (128 GiB) LRS Premium SSD disk provides 5000 IOPS and 200 MB/second bandwidth, which is same for P30 ZRS Premium SSD disk. Disk latency for ZRS is higher than that of Locally Redundant Storage (LRS) due to the cross zonal copy of data.


 


Get started


If you are interested in participating in the preview, request access by filling out this form. A list of regions where the feature is supported can be tracked on the documentation page. We will keep adding new regions throughout the public preview.


Review the ZRS disks preview documentation to learn how to do the following:



  1. Create a VM with ZRS OS and data disks.

  2. Create multiple VMs in different zones with a shared ZRS disk.

  3. Create VMSS with ZRS OS and data disk.

Brought to you by Dr. Ware, Microsoft Office 365 Silver Partner, Charleston SC.

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