Earlier this year, Microsoft introduced the preview of the zone-redundant storage (ZRS) option for Azure managed disks to further improve the reliability of their infrastructure, and now it is released into general availability (GA).
Azure Disk Storage is Microsoft’s high-performance, durable block storage for Azure Virtual Machines. It offers four disk storage options for the cloud—–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 customers to replicate data three times within a single data center in the selected region - protecting data against server rack and drive failures.
With ZRS, customers can increase availability for their workloads through synchronous replication of block storage across three availability zones in a region - it enables their disks to tolerate zonal failures, which may occur due to natural disasters or hardware issues. Moreover, a ZRS disk can be attached to a virtual machine (VM) in a different zone if a zone goes down. Furthermore, ZRS disks can also be shared between VMs for improved availability with clustered or distributed applications like SQL FCI and SAP ASCS/SCS.
In a Microsoft Azure blog post, the author Aung Oo, general manager, Azure Storage, explains the ZRS option:
Using Availability Zones for VMs, you can allocate primary and secondary VMs in different zones for higher availability and attach a shared ZRS disk to the VMs in different zones. If a primary VM goes down due to a zonal outage, Windows Server Failover Cluster (WSFC) will quickly failover to the secondary VM providing increased availability to your application. Customers can also use ZRS with shared disks for their Linux-based clustering applications that use IO fencing with SCSI persistent reservations.
Other public cloud providers like AWS and Google also offer managed disks on their platforms, including high availability options. AWS, for instance, has Amazon EBS Provisioned IOPS Volume, which provides the availability of five nines, while Google with Persistent Disk also has several availability options.
ZRS is currently available for the Premium SSD, and Azure Standard SSD disks and pricing details are available on the Azure Disk Storage pricing page. Furthermore, ZRS is available in West Europe, North Europe, West US 2, and France Central regions, with more regional availability to come.