Bad Sector Remapping Effect on Retrieval Rates:

Disks have spare sectors; disk controller remaps bad sectors transparently to spare area (defect management). List maintained in defect map (P-list, G-list). When mapped, logical block accessed via redirect.

Effect on retrieval:

• Sequential access: Remapped sectors are at different physical location (spare area elsewhere), so sequential scan that was contiguous becomes random seek to spare, increasing seek time, breaking sequentiality, lowering throughput especially for large sequential reads.
• Random access: Minor impact - still one seek, but may add slight latency due to lookup and possible extra seek to spare cylinder.
• Caching: If remapped sector cached, less impact, but first access incurs penalty.
• Throughput drops proportionally to number of remapped sectors; heavily remapped disk sees degraded sequential rate (e.g., 10-30% slower).

Mitigation: Controller maintains translation table; OS unaware but performance variance observed. SMART monitors reallocated count.