AZ-900 Practice Question 6: Storage Redundancy Options
Microsoft Azure Fundamentals (AZ-900) · Test 1 · question 6 of 10
A healthcare provider stores patient records in an Azure Storage account. A regulator requires that every copy of the data stay inside the primary Azure region, and an internal resiliency standard requires the data to stay readable and writable if an entire datacenter in that region is lost. Which redundancy option meets both requirements at the lowest cost?
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Answer:
ZRS writes each object synchronously across three or more availability zones in the primary region. Nothing leaves the region, which satisfies the regulator, and because the copies sit in separate zones the data stays available for both reads and writes when a whole datacenter or zone goes down. Microsoft explicitly recommends ZRS when replication must be restricted to one region for data governance reasons.
Option A, LRS, keeps all three copies in a single physical datacenter. It also never leaves the region, but a fire or flood in that datacenter can make every replica unavailable, so it fails the resiliency requirement. Options B and C both geo-replicate to a paired secondary region hundreds of miles away, which breaks the residency requirement: GRS uses LRS in the primary region plus asynchronous copy to the secondary, and GZRS uses ZRS in the primary region plus that same secondary copy. GZRS would meet the availability bar, but it is more expensive than ZRS and still moves data out of the region.
Reference: Azure Storage redundancy