A server has a disk array controller with battery-backed cache. Which of the following will MOST likely happen if the server loses power?

Question

Options

• AInformation in cache will be written to disk once the server regains power, assuming the
• BAll information in cache is lost, even if the battery has a change.
• CThe battery will supply power to the disk array in the event of a power failure, and cache will
• DInformation in cache will be transferred to firmware, and no information will be lost.

• A
  87% (26)
• B
  3% (1)
• C
  7% (2)
• D
  3% (1)

Explanation

A battery-backed write cache (BBWC) on a disk array controller stores pending writes in volatile DRAM to improve write performance. The onboard battery (or supercapacitor) provides just enough power to keep that cache alive during a power outage - it does NOT power the entire disk array. When power is restored, the controller detects the preserved cache and flushes those writes to disk before resuming normal operation. This makes BBWC an essential enterprise feature: you get the speed benefit of write caching with no data loss risk, provided the battery still holds a charge. Answer B is wrong because the battery's whole purpose is to prevent cache loss. Answer C is wrong because the battery only powers the cache chip, not the full disk array. Answer D is wrong because cache data is not transferred to firmware - firmware is non-volatile code storage, not a data buffer.

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