File Organization

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File organization is an attribute of files that reflects the way records are accessed and transferred to programs from storage (in blocks or buckets.

There are three types of file organizations available in OpenVMS:

If you use the sequential file organization, the multiblock run-time option allows multiple blocks to be transferred during a single I/O operation. Relative files and indexed files use buckets to transfer records. A bucket is a storage structure, consisting of 1 to 63 blocks, used for building and processing relative and indexed files.

Different record access modes are supported by different file organizations:

File Organization
Access Mode Sequential Relative Indexed
Sequential Yes Yes Yes
Random by relative record number Permitted with fixed-length record format on disk devices only Yes No
Random by key value No No Yes
Random by record file access Permitted on disk devices only Yes Yes Yes