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There is no downtime when you switch between different storage redundant options.
Switch between types of replication
If you need to migrate your storage account from LRS to ZRS in the primary region with no application downtime, you can request a live migration from Microsoft. To migrate from LRS to GZRS or RA-GZRS, first switch to GRS or RA-GRS and then request a live migration. Similarly, you can request a live migration from GRS or RA-GRS to GZRS or RA-GZRS. To migrate from GRS or RA-GRS to ZRS, first switch to LRS, then request a live migration.
During a live migration, you can access data in your storage account with no loss of durability or availability. The Azure Storage SLA is maintained during the migration process. There is no data loss associated with a live migration. Service endpoints, access keys, shared access signatures, and other account options remain unchanged after the migration.
Geo-redundant storage (GRS) copies your data synchronously three times within a single physical location in the primary region using LRS. It then copies your data asynchronously to a single physical location in the secondary region. Within the secondary region, your data is copied synchronously three times using LRS.
Is there any data loss associated with the migration?
There is no data loss associated with the migration. During the migration process, you have the same level of durability and availability SLA as you normally do
Hope this helps!
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