Datalohkoja

Datalohkoja are the basic storage units used by a file system or data storage system to hold file data. Each datalohko is a fixed-size block that can be independently read or written. In most implementations, a block contains a payload area for data and a small header with metadata such as the block’s size, status, and pointers to other blocks.

Blocks are addressed by a unique identifier and are assembled into files by allocation tables or inodes. To represent a file, a filesystem may use direct block pointers, indirect pointers to further blocks, or extents that describe ranges of contiguous blocks. This enables files of varying sizes and supports efficient metadata handling.

Block sizes vary by system, commonly ranging from 512 bytes to several kilobytes; larger blocks reduce metadata overhead but can decrease space efficiency for small files. Allocation strategies include contiguous allocation, extent-based allocation, and linked allocation. Fragmentation and variability in free space influence performance and defragmentation needs.

In local and distributed storage, datalohkoja serve as the primary units for storing actual data blocks. In distributed systems, blocks may reside on different storage nodes and be reassembled by the system into a complete file. Some designs distinguish data blocks from dedicated metadata blocks used by the file system itself.

Data integrity features such as checksums, journaling, and copy-on-write mechanisms aim to prevent corruption during writes and crashes. Journaling records changes before they are applied; copy-on-write preserves previous versions. Defragmentation and reclamation algorithms recover or reuse freed blocks as files are created and deleted.