NS0-157 Question #58: Real Exam Question with Answer & Explanation

The correct answer is B: 0 GB. When a volume's space-guarantee is set to none, no space is pre-allocated from the aggregate, and any LUN space-reserve setting inside that volume is overridden, resulting in 0 GB of guaranteed available space before data is written.

Storage Provisioning and Management

Question

You create a 1000 GB volume with space-guarantee set to none and fractional-reserve set to 0. In that volume you create a 400 GB LUN with space-reserve enabled. How much space is available in the volume before data is written to the LUN?

Options

A400 GB
B0 GB
C600 GB
D1000 GB

Explanation

When a volume's space-guarantee is set to none, no space is pre-allocated from the aggregate, and any LUN space-reserve setting inside that volume is overridden, resulting in 0 GB of guaranteed available space before data is written.

Common mistakes.

A. 400 GB would only be the correct answer if the volume had sufficient guarantee to honor the LUN reservation and 400 GB of free space remained after that deduction, which does not apply when guarantee is none.
C. 600 GB would be the free space remaining after a 400 GB space-reserved LUN in a fully guaranteed 1000 GB volume, but this assumes the volume guarantee is set to 'volume' or 'file', not 'none'.
D. 1000 GB would be the available space only if no LUN reservation were in effect and the volume guarantee was 'volume', neither of which is true in this configuration.

Concept tested. ONTAP volume space-guarantee none overriding LUN space-reserve

Reference. https://docs.netapp.com/us-en/ontap/volumes/space-guarantee-concept.html

Topics

#space guarantee#fractional reserve#thin provisioning#LUN space reservation

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