Sync-mark detection error recovery

Abstract

Sync-mark (SM) detection recovery techniques for HDDs tend to be slow and cumbersome. Typical approaches often require an entire read command to be aborted and multiple subsequent read commands with significant firmware intervention. Should a data sector be unreadable, an example recovery technique for HDDs is recursive read averaging (RRA). Using RRA, samples for failed sector reads are stored in memory. When a sector is subsequently read, the samples are averaged and replace the prior sample stored in memory. The averaged samples are then used to decode the sector. Should SMs associated with data fragments making up a sector be unreadable, the data fragments are unreadable, rendering the sector unreadable. The systems and methods described herein are used to recover previously unreadable SMs. When updated data fragments are subsequently recombined, the confidence level in the overall sector is improved, which increases the likelihood of a successful decode of the sector.