Earlier this year, Microsoft introduced the zonal redundant storage (ZRS) option preview for Azure managed disks to further improve the reliability of their infrastructure, and it is now available in general availability (GA).

Azure Disk Storage is Microsoft’s high-performance, durable block storage for Azure virtual machines. It offers four cloud disk storage options: Ultra Disk Storage, Premium SSD, Standard SSD, and Standard HDD. Additionally, with these disk storage options, customers can now choose between two storage redundancy options, ZRS and Locally Redundant Storage (LRS). The latter allows clients to replicate data three times in a single datacenter in the selected region, thus protecting the data against server rack and disk failures.

With ZRS, customers can increase the availability of their workloads through synchronous block storage replication across three Availability Zones in a region – this allows their disks to tolerate zone failures, which can occur due to natural disasters or material problems. Additionally, a ZRS disk can be attached to a virtual machine (VM) in a different zone if one zone fails. Additionally, ZRS disks can also be shared between virtual machines for improved availability with clustered or distributed applications such as SQL FCI and SAP ASCS / SCS.

In a Microsoft Azure blog post, author Aung Oo, Managing Director, Azure Storage, explains the ZRS option:

Using Availability Zones for virtual machines, you can allocate primary and secondary virtual machines in different zones for higher availability and attach a shared ZRS disk to virtual machines in different zones. If a primary virtual machine crashes due to a zone outage, the Windows Server Failover Cluster (WSFC) will quickly fail over to the secondary virtual machine, providing increased availability for your application. Customers can also use ZRS with shared disks for their Linux-based clustering applications that use IO fencing with SCSI persistent reservations.

Source: https://azure.microsoft.com/en-us/blog/improve-availability-with-zoneredundant-storage-for-azure-disk-storage/

Other public cloud providers like AWS and Google also offer managed disks on their platforms, including high availability options. AWS, for example, has Amazon EBS Provisioned IOPS Volume, which offers the availability of five nines, while Google with Persistent Disk also offers several availability options.

ZRS is currently available for Premium SSD, and Azure Standard SSDs and pricing details are available on the Azure Disk Storage pricing page. Additionally, ZRS is available in Western Europe, Northern Europe, Western US 2, and Central France regions, with more regional availability to come.