How is cell-to-cell communication implemented in an Oracle Exadata Database Machine?

Question

Options

• AThrough flash cache.
• BThrough the Infiniband switch.
• CThrough onboard memory.
• DThere is never any cell-to-cell communication in an Exadata Storage Server.

• A
  4% (1)
• B
  15% (4)
• C
  7% (2)
• D
  74% (20)

Explanation

No cell-to-cell communication is ever done or required in an Exadata configuration. If data from both cells are required then do they join at the idb layer. From the Oracle Exadata white paper: "No cell-to-cell communication is ever done or required in an Exadata configuration."and a few paragraphs later: "Data is mirrored across cells to ensure that the failure of a cell will not cause loss of data, or inhibit data accessibility" Can both these statements be true and would we need to purchase a minimum of two cells for a small-ish ASM environment? Cells are entirely autonomous and the two statements are true indeed. Consider two ASM disks out in a Fibre Channel SAN. Of course we know those two disks are not "aware of each other" just because ASM is using blocks from each to perform mirroring. The same is true for Oracle Exadata Storage Server cells and the drives housed inside them. As for the second part of the questions, yes, you must have a minimum of two cells. In spite of the fact that Cells are shared nothing (unaware of each other), ASM is in fact Cell-aware. ASM is intelligent enough to not mirror between 2 drives in the same Cell.

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