Storage device with inline address indirection metadata storage

摘要

Methods are described that allow disk drives, such as shingle-written magnetic recording (SMR) drives, to recover an Indirection Address Table mapping of LBAs to PBAs after an emergency power off (EPO). Indirection Address Table (IAT) snapshots are periodically written inline with user data stores, and in one embodiment Cumulative Delta Lists (CDLs) with incremental address update information are stored between snapshots. In an embodiment of the invention, when an imminent loss of power is detected, the current CDL, covering IAT updates not yet written to disk, is saved to a nonvolatile memory. The IAT snapshots combined with the set of CDLs provide the information needed to recreate the current Indirection Address Table when power is restored after an emergency power loss. In an alternative embodiment the CDL is obviated by including metadata in the sector that encodes the address indirection mapping and the last snapshot ID.

主权项

1. A method of operating a data storage device having an Indirection Address Table mapping logical block addresses (LBAs) to physical block addresses (PBAs), the method comprising:
periodically writing a snapshot of the Indirection Address Table on a disk inline with user data being written in a buffer on the disk, with the snapshot being written after a first block of user data has been written in the buffer and before a second block of user data so that the snapshot is positioned between first and second blocks of user data, each snapshot including a snapshot ID that identifies a last snapshot from earlier snapshots; and after each snapshot is written, making a Delta List that contains a set of entries that record subsequent changes to the Indirection Address Table after the first block of user data has been written, with entries mapping at least one LBA to a PBA for the second block of user data and periodically writing the Delta List to the buffer on the disk, each Delta List including the snapshot ID that identifies the last snapshot.