A storage administrator performs a monthly performance analysis of a Dell Unity XT storage array using CloudlQ insight reports. Three LUNs are set with a Host IO Limits policy The administrator…

Question

Options

• ATest_LUN was expanded by 10o GB and a Density-based Host IO limit policy was set for all three
• BTest_LUN was expanded by 100 GB and a Density-based Host IO limit policy was set only for
• CAnother Absolute Host lO limit policy with additional 10oo IOPS was set on Test_LUN.
• DHost IO limit of Test LUN was edited and the limit was increased by 1000 IOPS.

• A
  11% (5)
• B
  60% (28)
• C
  4% (2)
• D
  26% (12)

Explanation

Option B is correct because a Density-based Host IO Limit scales IOPS proportionally with LUN capacity (measured in IOPS per GB). When Test_LUN was expanded by 100 GB and had this policy applied exclusively to it, the effective IOPS ceiling automatically increased - at 10 IOPS/GB density, a 100 GB expansion yields exactly +1000 IOPS, which matches the observed spike.

Why the distractors are wrong:

• A is wrong because if the density-based policy applied to all three LUNs equally, you'd need all three to be expanded to see a uniform spike - but only Test_LUN changed. The "all three" scope is the flaw.
• C is wrong because Unity XT does not support stacking multiple Host IO Limit policies on a single LUN; only one policy can be active at a time.
• D is wrong because raising an Absolute IO limit ceiling by 1000 IOPS doesn't automatically cause throughput to spike - it merely removes a restriction; actual workload demand would need to fill that headroom independently.

Memory tip: Think "Density = Dynamic." A Density-based limit rides with the LUN size - expand the LUN, expand the IOPS cap automatically. An Absolute limit is a fixed number that never moves unless manually changed.

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