Editing Tape library (section)

== Manual era ==
[[File:NDOC magnetic tape library.jpg|thumb|A manual magnetic tape library, common in the 1960s and 1970s. Rolling carts are used by staff to transfer tapes between the racks in the library and the computer room where the tape drives reside.]]

=== Tapes and batch processing ===
In the [[mainframe computer]] era, especially the [[IBM mainframe]], the most common format in use was the [[9-track tape]].<ref name="popkin-pike"/>
Some large application systems could require scores of different tapes as part of their batch job runs.<ref name="mccracken"/>

In the data processing applications of the era, the [[master file]]s for such things as employee payroll information, supplies and stores inventory, or customer accounts were typically kept on tape.<ref name="mcquillen"/><ref name="stern-stern"/>  Batch jobs to update these master files would take the existing tape master file as input and write out a new tape master file as output.<ref name="ashley-fernandez">{{cite book | title=Job Control Language: A Self-Teaching Guide | first1=Ruth | last1=Ashley | first2=Judi N. | last2=Fernandez | publisher=John Wiley & Sons | location=New York | date=1978 | isbn=0-471-03205-0 | page=43 }}</ref> In addition, the set of update transactions themselves might constitute a second input tape.<ref name="mcquillen">{{cite book | title=System/360–370 Assembler Language (OS) | first=Kevin | last=McQuillen | publisher=Mike Murach & Associates | location=Fresno, California | date=1975 | lccn=74-29645 | page=302}}</ref> The master file output of one update job would then be the master file input to the next time the job is run, perhaps a day, a week, or a month later.<ref name="popkin-pike"/> The tapes representing a few past iterations of a master file would typically be retained, in case a problem with the latest version were to be discovered and the job had to be rerun.<ref name="popkin-pike"/>

=== Role of tape libraries and librarians ===
[[Image:Tape Retention Scratch Control triplicate form.jpg|thumb|upright=0.7|left|Tape Retention / Scratch Control form, in triplicate]]

Mainframe computer installations often had a separate room, the tape library, to house their racks and cabinets of tapes.<ref name="popkin-pike"/> The typical workflow for running a batch job was to go into the library, pull certain tapes off the racks there and load them onto a rolling cart, move the cart into the computer area, mount the tapes onto tape drives for a production run, take the tapes off the drives when the run was over, move the cart back to the library, and put the tapes back on the library racks.  Such tape libraries existed at most computer installations.<ref name="conway-gries"/>

Even a modestly sized computer installation could have hundreds of tapes,<ref name="stern-stern">{{cite book | title=Structured COBOL Programming | first1=Nancy | last1=Stern | first2=Robert A. | last2=Stern | publisher=John Wiley & Sons | location=New York | edition=3rd | date=1980 | isbn=0-471-04913-1 | pages=494, 496, 498&ndash;499 }}</ref>
and library sizes of several thousand reels of tapes were commonplace.<ref name="conway-gries"/> 
And they could be much larger:  by the mid-1970s, the [[U.S. Census Bureau]] and [[NASA]] each had tape libraries with around one million tape reels in them.<ref name="mccracken"/>
The person in charge of all this was typically called the [[tape librarian]].<ref name="popkin-pike"/><ref name="stern-stern"/> 

In this era, there were no automated tape delivery and mounting systems, and so this action had to be done by [[computer operator]]s.<ref name="conway-gries">{{cite book |last1=Conway |first1=Richard  |last2=Gries |first2=David |year=1973 |title=An Introduction to Programming: A Structured Approach using PL/1 and PL/C |publisher=Winthrop |location=Cambridge, Massachusetts | pages=333&ndash;334 }}</ref>
These people were the ones responsible for mounting tapes onto [[tape drive]]s as part of running a job.<ref name="popkin-pike"/>
Even careful computer operators could sometimes mount the wrong tape as input to a job or present the reels of a multi-tape dataset out of order.<ref name="mccracken">{{cite book| title=A Simplified Guide to Structured COBOL Programming| publisher=John Wiley & Sons|location=New York| year=1976 | isbn=0-471-58284-0  | author-first=Daniel D. | author-last=McCracken | pages=259, 264 }}</ref> Overwriting a tape that was meant to be preserved was another potential mistake.<ref name="stern-stern"/>

It was the tape librarian's responsibility to set up procedures for the handling of tapes to minimize the chances of errors taking place.<ref name="stern-stern"/>
As one book of the era wrote, "keeping track of the whereabouts of the tapes is a formidable and responsible job."<ref name="popkin-pike">{{cite book | title=Introduction to Data Processing | author-first=Gary S. | author-last=Popkin | author2-first=Arthur H. | author2-last=Pike | publisher=Houghton Mifflin Company | location=Boston | year=1977 | isbn=0-395-20628-6 | pages=149&ndash;151, 260&ndash;263 }}</ref>

=== Supporting software ===
{{seealso|Tape management system}}

Tape management systems of this era were software packages whose purpose was to help facilitate tape library operations and management. They kept track of data sets on tape, and produced reports indicating whether a data set should be retained on, or could be scratched from, a tape; they aided in the setup and running of scheduled production jobs, through such things as tape pull lists and pre-printed external gummed tape labels; and they kept track of the physical inventory of tape reels. The most popular of these packages was UCC-1 from [[University Computing Company]],<ref name="cw-jan1977">{{cite news | url=https://books.google.com/books?id=XEToBl0e2NIC&dq=%22ucc%22+%22honor+roll%22&pg=PA23 | title=Users Put 38 Packages on Honor Roll | first=Don | last=Leavitt | newspaper=Computerworld | date=January 17, 1977 | page=23 }}</ref> a product that was also known as the Tape Management System.<ref>{{cite news | url=https://books.google.com/books?id=JF4iQwmmCwYC&dq=%22university+computing%22+%22ucc-1%22&pg=PA35 | title=UCC-1 Tape Management Updated with Release 4.7 | newspaper=Computerworld | date=July 4, 1983 | page=35 }}</ref> It made several appearances on [[Datapro Research Corporation]]'s Software Honor Roll.<ref name="cw-jan1977"/> Another was Valu-Lib from [[Value Computing, Inc.]],<ref>{{cite news | url=https://books.google.com/books?id=esYk9fkCBWgC&dq=valu-lib+tape&pg=PA15
 | title='Valu-Lib' Can Run Tape Library, Can Interface With Scheduler | newspaper=Computerworld | date=May 16, 1973 | page=15 }}</ref><ref>{{cite news | url=https://books.google.com/books?id=aDCH6OPGmh8C&dq=valu-lib+tape&pg=PA32 | title='Valu Lib' Update Released For IBM 4300s, Series/36 | newspaper=Computerworld | date=December 19, 1983 | page=32 }}</ref>
and a third was TLMS II from [[Capex Corporation]].<ref>{{cite news | url=https://books.google.com/books?id=K1VUAAAAMAAJ&q=%22capex%22+%22tape+library%22 | title=uncertain | magazine=Infosystems | publisher=Hitchcock Publishing Company | year=1980 | volume=uncertain| page=90 | access-date=February 22, 2023 | archive-date=March 25, 2023 | archive-url=https://web.archive.org/web/20230325204700/https://books.google.com/books?id=K1VUAAAAMAAJ&q=%22capex%22+%22tape+library%22 | url-status=live }}</ref>

As use of the mainframe continued on into the following century, tape library management, both manual and automatic, was one element of the offerings of the [[Data Facility Storage Management Subsystem (MVS)]] from IBM.<ref>{{cite news | url=https://www.ibm.com/docs/en/zos/3.1.0?topic=libraries-introduction-tape-library-management | title=Introduction to tape library management | publisher=IBM | date=April 5, 2023 | access-date=November 1, 2023}}</ref>