Amazon Technologies, Inc.

Pure Storage, Inc.

Daniel Sladic

Peter E Kirkpatrick

Leonid Baryudin

Gordon James Coleman

Eric D Seppanen

Wei Tang

Phillip Peterson

Sujan Biswas

An indirection mapping data structure can maintain a mapping between logical block addresses used by a host computer and physical data storage locations on a solid state drive. Changes to the indirection mapping data structure can be stored in journals. When a journal is full, the journal can be stored to a predetermined location on the cluster block determined based on the number of entries stored by the journal, leading to a number of journals scattered throughout the cluster block at predetermined locations. Each physical chunk of media, whether written with data or marked as defective is journaled. Such a journaling scheme, where the journal locations are predetermined and each physical chunk of media is journaled is referred to as physical media-aware spatially coupled journaling. During replay the spatially coupled journals can be retrieved from the predefined locations within cluster blocks and used to rebuild the indirection mapping data structure.

Physical media aware spacially coupled journaling and replay

In a solid state drive, a journal may be associated with a cluster block, such that the journal stores updates to an indirection mapping data structure for that cluster block. The journals may be stored on the cluster block. During garbage collection these spatially coupled journals can be retrieved and used to determine the data written to each media location within the cluster block. Logical and physical address information can be determined from the journal content, and used to compare against the current mapping in the indirection mapping data structure, to determine the validity of each media location. Since the journals are physical media aware, this comparison can occur without the consultation of a bad block tracking structure. When a physical media address is deemed to hold valid data it will be relocated as part of garbage collection processing.

Garbage collection in solid state drives

Spatially coupled journals include information for every portion of physical media, including defective, or 'bad', blocks. Because data cannot be stored to bad blocks, a bad block table is needed before a solid state drive (SSD) can be accessed. Using the information already stored in the journals, the bad block table can be rebuilt following a loss of power. To ensure the journals can be located, a small seed can be stored in off band storage. The seed can include information pointing to a boot catalog stored on the SSD. The boot catalog can be used to determine the locations of journals, which may vary from their predetermined locations depending on the bad blocks of the drive. By storing a small seed, rather than an entire bad block table, the size of external storage needed to maintain the bad block table is reduced.

Bad block table recovery in a solid state drives

A storage device associated with a storage array may be identified. Information specifying an organization of data included in a data structure may be retrieved from the storage device. The data may be associated with characteristics of a plurality of data blocks of the storage device. A read operation or a write operation may be performed for the storage device based on the information specifying the organization of the data included in the data structure that is associated with the characteristics of the plurality of data blocks of the storage device.

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Daniel Sladic