Understanding Storage Account replication downtime

For Azure Storage, transitioning from Locally Redundant Storage (LRS) to another redundancy option can be achieved through two approaches: online conversion or manual migration. Online conversion, when supported, allows the change to be completed without service interruption. In contrast, manual migration requires a planned downtime, though it provides greater control over the timing of the process. According to Microsoft official guidance, downtime is unavoidable for manual migrations, while certain conversion paths can be executed seamlessly. The availability of online conversion depends on both the storage account type and the target redundancy configuration. Microsoft provides detailed documentation on the redundancy models say LRS, Zone‑Redundant Storage (ZRS), Geo‑Redundant Storage (GRS), Read‑Access GRS (RA‑GRS), Geo‑Zone‑Redundant Storage (GZRS), and Read‑Access GZRS (RA‑GZRS) along with their respective trade‑offs:

Change how a storage account is replicated - Azure Storage | Microsoft Learn