Last week, Microsoft announced a reduction in Azure Archive Storage prices by up to 50 percent, in a bid to provide the most cost-effective storage access. Today, the tech giant has unveiled a new data redundancy type for Azure block blob storage in public preview, dubbed Geo-zone-redundant storage (GZRS).
For those unaware, Azure Storage accounts contain several redundancy options that can be used in the repairing process in cases where corrupted data is detected. These include locally redundant storage (LRS), zone-redundant storage (ZRS), and more which shall be mentioned further along. Each of these may be more suitable than the others depending upon the type of scenario being faced.
GZRS is being touted by Microsoft as a well-balanced option with high performance, high availability, and disaster recovery. Reading data is still possible with read-access GZRS (RA-GZRS) even if a whole region becomes unavailable, while a minor zone failure in primary regions does not deter data access capabilities in any form. Moreover, this data redundancy type also offers increased resiliency through the following techniques:
- Synchronously writing three replicas of your data across multiple Azure Availability Zones, such as zone-redundant storage today, protecting from cluster, datacenter, or entire zone failure.
- Asynchronously replicating the data to another region within the same geo into a single zone, such as locally redundant storage, protecting from a regional outage.
The following table offers a comparison between the various storage redundancies in terms of their utilization across different situations:
| Scenario | Locally redundant storage | Geo-redundant storage | Read Access geo-redundant storage | Zone-redundant storage | Geo Zone Redundant Storage | Read Access Geo Zone Redundant Storage |
| Node unavailability within a data center | Yes | |||||
| An entire data center (zonal or non-zonal) becomes unavailable | No | Yes (failover is required) | Yes | Yes | ||
| A region-wide outage | No | Yes (failover is required) | No | Yes (failover is required) | ||
| Read access to your data (in a remote, geo-replicated region) in the event of region-wide unavailability | No | No | Yes | No | No | Yes |
| Designed to provide X% durability of objects over a given year | at least 11 9"s | at least 16 9"s | at least 12 9"s | at least 16 9"s | ||
| Supported storage account types | GPv2, GPv1, Blob | GPv2 | ||||
| Availability SLA for read requests | At least 99.9% (99% for Cool Access Tier) | At least 99.99% (99.9% for Cool Access Tier) | At least 99.9% (99% for cool access tier) | At least 99.99% (99.9% for Cool Access Tier) | ||
| Availability SLA for write requests | At least 99.9% (99% for Cool Access Tier)
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Notably, GZRS prices are discounted in the preview phase, and will be updated when it reaches general availability. Furthermore, the storage option is only available for general-purpose v2 accounts in some U.S. and European regions for now. Although the documentation notes only U.S. East and Europe West being the chosen regions at the moment, switching regions in the drop-down menu under storage options on the pricing page reveals pricing details for some other regions as well. Namely, these are Central U.S., West U.S. 2, and North Europe.
Finally, another thing to be kept in mind with regards to GZRS availability is that only "hot" access tiers are being offered for now. These are optimized for storing frequently accessed data. Furthermore, cost per GB/month for GZRS begins in the ~$0.02 vicinity, though this varies with region, types of required features, and other factors.
GZRS accounts can be created using Azure portal, Azure CLI, Azure PowerShell, and more methods. For those migrating from other storage redundancies, more information including detailed conversion processes is available here.