NS0-157 Question #320: Real Exam Question with Answer & Explanation

The correct answer is E: One of the aggregates will be overwritten and you will lose any data changed on it after the split.. When two previously split aggregates are rejoined in Data ONTAP, one aggregate is completely overwritten, and all data written to that aggregate after the split is permanently lost.

Storage Provisioning and Management

Question

What happens when two aggregates are rejoined?

Options

AIt is not possible to rejoin aggregates.
BData ONTAP will always retain data from the newest aggregate.
CBoth aggregates revert to the last common snapshot before the split.
DYou will have a large new aggregate containing all volumes from both aggregates.
EOne of the aggregates will be overwritten and you will lose any data changed on it after the split.

Explanation

When two previously split aggregates are rejoined in Data ONTAP, one aggregate is completely overwritten, and all data written to that aggregate after the split is permanently lost.

Common mistakes.

A. Rejoining aggregates is a supported Data ONTAP operation; the concern is not impossibility but rather the guaranteed data loss it causes.
B. Data ONTAP does not selectively preserve the newer aggregate's data - one aggregate is unconditionally overwritten regardless of relative age.
C. Aggregate rejoin does not roll both aggregates back to a common snapshot checkpoint; only one aggregate is overwritten to match the other's state at split time.
D. Rejoining aggregates does not produce a merged aggregate containing all volumes from both sides; one side's post-split changes are simply discarded.

Concept tested. Data ONTAP aggregate rejoin data loss behavior

Reference. https://library.netapp.com/ecmdocs/ECMP1196890/html/index.html

Topics

#aggregate rejoin#aggregate split#data overwrite#aggregate management

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