LBA Status Log

Overview

The LBA Status Log is an HDD feature that differentiates between good LBAs, unhealthy/degrading LBAs, and inaccessible LBAs, returning a categorized list the host can use to copy or protect data before a head fails completely. It enables proactive, host-managed data relocation rather than reactive recovery. As of October 2025 the drive-side implementation exists but ecosystem support is still in development — the host-side integration is not yet complete.

In the context of extending depopulation to CMR drives (Solution 2), the LBA Status Log underpins host-managed relocation: the host can use the WRITE GATHERED EXT command to move data within the device without consuming data center network infrastructure, minimizing bandwidth impact. The cost is scale: a single failing head in a 100-drive enclosure could generate roughly 40,000 remap entries per drive — about 4 million entries per enclosure — creating significant host-management overhead.