nand-copyback · shipping · also copy-back, internal data move, IDM

NAND copyback

NAND copyback relocates page data through an on-chip buffer to a destination page without transferring the payload to an external controller.

The studied implementations constrain source and destination placement; a host copy command does not establish that NAND copyback occurred. Bypassing controller ECC can preserve read errors in the new copy, so the correction path must be specified.

Relations

related

nand-flash, garbage-collection, write-amplification, ftl, ldpc, data-retention

Advantages

• Can avoid the off-chip payload transfers used by a controller-mediated relocation. [2]

Limitations

• Placement restrictions are device-specific; historical odd/even rules must not be applied to every NAND generation. [2]
• Restricted-copyback research uses conditional consecutive-copy budgets, not a universal safe count. [1]

Citations

1. Hong, Kim, Park, Jung and Kim. Revitalizing Copybacks in Modern SSDs: Why and How. Author manuscript arXiv:1810.04603v1, 2018, sections 3-5. (accessed 2026-10-11)
2. Hu, Jiang, Feng, Tian, Luo and Zhang. Performance Impact and Interplay of SSD Parallelism through Advanced Commands, Allocation Strategy and Data Granularity. ICS 2011, sections 2.2 and 4.3. (accessed 2026-10-11)
3. Han, Gwak, Shin and Hwang. ZNS+: Advanced Zoned Namespace Interface for Supporting In-Storage Zone Compaction. OSDI 2021, sections 2.1 and 3.3.1. (accessed 2026-10-11)
4. Hesela: NAND copyback, faster relocation is not fewer writes (accessed 2026-10-11)
5. Hesela illustrative copyback payload accounting: assumptions, results and model hash (accessed 2026-10-11)

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