subblocks

Subblocks are subdivisions of a larger data block used in computing to manage data at a finer granularity than the parent unit. A block may be a fixed-size unit used by storage devices, memory allocators, or network protocols, while subblocks are smaller segments contained within that unit. Subblocks allow partial updates, finer-grained metadata, and parallel or independent access to portions of data.

In storage and filesystems, a block can be split into subblocks to support selective rewriting and to improve deduplication efficiency. Each subblock has an offset within the parent block and a length, and may carry its own metadata such as a checksum, version stamp, or type tag. Addressing schemes map subblock coordinates to the parent block offset, enabling targeted reads or writes without touching the entire block.

In memory management and caching, subblocks enable more flexible allocation within a fixed-size page or block, reducing fragmentation and allowing parallel I/O operations. In data processing and transmission, subblocks are used to segment data for parallel processing, streaming, or error containment; subblock-based compression and encoding can improve compression ratios or resilience.

Benefits include reduced write amplification, better cache locality, and more efficient access patterns for workloads with localized updates. Trade-offs involve increased metadata overhead, potential fragmentation, and added complexity in data management and integrity checks.

See also: block, sub-block deduplication, block device, fragmentation.