Talk:Record-oriented filesystem

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I'm confused about this article, is it a FILESYSTEM (like FAT, ext2, ReiserFS) or a FILE-FORMAT (magic numbers, file extension) system? Improfane

A: It's not about a specific file system, but rather the whole class of filesystems that support record-oriented operation. The key point is that the system calls used to access files are designed to access records, rather than chunks of data read or written in application-specific formats. Most mainframe operating systems support a rich variety of record-oriented record formats. Most commonly, records are fixed in length within any given file, or a file may have variable-length records. Unlike the stream-oriented systems found on systems like Unix, PC-DOS, Windows, and Mac, the data in the file is accessed strictly in terms of records. Variable-length records are preceded by a (usually) binary byte-count, and may contain any coded bytes at all, both binary and characters. There is no concept of an "end of line" delimiter, such as a carriage-return character.

Some people, particularly Unix advocates, dismiss record-oriented file systems as being based on punched-card technology, and therefore presumably "old-fashioned." The Unix-like stream-oriented approach is modelled after another 19th century technology, that of the paper-tapes used by the printing telegraph, used to mechanize the transmission of telegrams. These started being used for computers in the form of Teletype machines used as inexpensive input devices by the mini-computers of the '60s and '70s.

For its part, the Hollerith punched card was at least originally conceived for computational purposes.

This article, it seems to me, was written by a Unix advocate who wished to diminish the advantages of record-oriented file access methods. It is clearly not NPOV. I plan to fix it, when I find time to address the matter properly.

--RussHolsclaw 04:23, 12 February 2006 (UTC)

I agree! Moreover, terminology: does an IBM mainframe OS even use a filesystem? You have VTOCs, catalogs, data sets, but file system? Never heard of that. Source needed. --Kubanczyk 09:05, 7 October 2007 (UTC)

IBM calls file systems Access Methods.

Paper tape as used for text message transmission actually contain individual records which are delimited by various control characters. Each line of text (aka record) is terminated be a carriage-return character (which sends the print head to the left) and a line-feed character which rolls the paper platen up a line in position for the next line.

A better example of a datastream used in punched tape is in a numerical controlled machine tools NC These use a stream of commands to define which cutting tool to use, the starting position, subsequent points along the cutting path and other control information.

A record oriented file has several advantages. After a program writes a collection of data as a record the program that reads that record has the understanding of that data as a collection. Although it is permitted to read only the beginning of a record, the next sequential read returns the next collection of data (record) that the writer intended to be grouped together. Another advantage is that the record has a length and there is no restriction on the bit patterns composing the data record, i.e. there is no delimiter character.

There is a cost associated with record oriented. The length definition takes up space. On a magnetic tape that definition takes the form of an inter-record gap. On a disk a meta data area must be allocated. This is minimal in a file where all the records are the same length. On a file composed of varying length records a maximum record length is defined to determine the size of the length metadata associated with each record.

DGerman (talk) 01:09, 7 February 2008 (UTC)

After adding all this information in the discussion page, I decided it best to basically rewrite the article. I have saved the original article if anyone wants it. It is also available in the wiki history. Tired now. In the future I may locate and include some references. DGerman (talk) 02:15, 7 February 2008 (UTC)