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Systems & Data Center · Intermediate

Write-Back Cache

A caching mode where writes are acknowledged once stored in cache, then flushed to disk later, improving write performance.

Definition

Write-back requires battery- or flash-backed cache to avoid data loss during power failure. Write-through acknowledges only after data reaches disk, which is safer but slower.

Example

A RAID controller disables write-back and falls back to write-through when its cache battery fails.

Exam tip

Write-back without protected cache risks data loss on power failure.

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