Azure Storage redundancy

The data in your Microsoft Azure storage account is always replicated to ensure durability and high availability. Azure Storage copies your data so that it is protected from planned and unplanned events, including transient hardware failures, network or power outages, and massive natural disasters. You can choose to replicate your data within the same data center, across zonal data centers within the same region, or across geographically separated regions.

Replication ensures that your storage account meets the Service-Level Agreement (SLA) for Storage even in the face of failures. See the SLA for information about Azure Storage guarantees for durability and availability.

Choosing a redundancy option

When you create a storage account, you can select one of the following redundancy options:

The following table provides a quick overview of the scope of durability and availability that each replication strategy will provide you for a given type of event (or event of similar impact).

Scenario LRS ZRS GRS RA-GRS
Node unavailability within a data center Yes Yes Yes Yes
An entire data center (zonal or non-zonal) becomes unavailable No Yes Yes Yes
A region-wide outage No No Yes Yes
Read access to your data (in a remote, geo-replicated region) in the event of region-wide unavailability No No No Yes
Designed to provide __ durability of objects over a given year at least 99.999999999% (11 9's) at least 99.9999999999% (12 9's) at least 99.99999999999999% (16 9's) at least 99.99999999999999% (16 9's)
Supported storage account types GPv2, GPv1, Blob GPv2 GPv2, GPv1, Blob GPv2, GPv1, Blob
Availability SLA for read requests At least 99.9% (99% for cool access tier) At least 99.9% (99% 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) At least 99.9% (99% for cool access tier) At least 99.9% (99% for cool access tier) At least 99.9% (99% for cool access tier)

For pricing information for each redundancy option, see Azure Storage Pricing.

For information about Azure Storage guarantees for durability and availability, see the Azure Storage SLA.

Note

Premium Storage supports only locally redundant storage (LRS).

Changing replication strategy

You can change your storage account's replication strategy by using the Azure portal, Azure Powershell, Azure CLI, or one of the Azure client libraries. Changing the replication type of your storage account does not result in down time.

Note

Currently, you cannot use the Portal or API to convert your account to ZRS. If you want to convert your account's replication to ZRS, see Zone-redundant storage (ZRS) for details.

Are there any costs to changing my account's replication strategy?

It depends on your conversion path. Ordering from cheapest to the most expensive redundancy offering we have LRS, ZRS, GRS, and RA-GRS. For example, going from LRS to anything will incur additional charges because you are going to a more sophisticated redundancy level. Going to GRS or RA-GRS will incur an egress bandwidth charge because your data (in your primary region) is being replicated to your remote secondary region. This is a one-time charge at initial setup. After the data is copied, there are no further conversion charges. You will only be charged for replicating any new or updates to existing data. For details on bandwidth charges, see Azure Storage Pricing page.

If you convert your storage account from GRS to LRS, there is no additional cost, but your replicated data is deleted from the secondary location.

If you convert your storage account from RA-GRS to GRS or LRS, that account is billed as RA-GRS for an additional 30 days beyond the date that it was converted.

See also