What is the default exposed LUN0 used for?

Question

Options

• AStorage Array Controller Device
• BvVol protocol endpoint
• CInternal migration reserve LUN
• DNVMe Discovery Controller

• A
  91% (30)
• B
  3% (1)
• C
  6% (2)

Explanation

LUN0 is reserved as the Storage Array Controller Device (SACD) - a management-level logical unit that hosts use to communicate with and query the storage array controller itself, not to store data. It acts as the "front door" to the array, allowing initiators to discover array capabilities and configuration.

• B is wrong because vVol protocol endpoints are special LUNs used in VMware Virtual Volumes (vVols) environments specifically as an I/O proxy, and they are not LUN0 by default.
• C is wrong because internal migration reserve LUNs are vendor-specific constructs used during data migration, unrelated to the default LUN0 purpose.
• D is wrong because the NVMe Discovery Controller is an NVMe-oF concept used to locate NVMe subsystems - a completely different protocol mechanism.

Memory tip: Think of LUN0 as "zero data, all control" - it's the controller device, not a storage destination. If you see a LUN you can't write user data to, it's likely the SACD sitting at LUN0 managing the array.

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