TAPE-REPLACEMENT-LEVEL— This is the point at  which  the  number  of  errors  exceeds  the  rejection level. Maintaining Magnetic Media Maintaining   media   involves   using   specialized library   equipment   to   clean,   certify,   and   degauss magnetic media. It also involves seeing that media is in usable   condition. The   duties   and   responsibilities include the following: Splicing leaders onto magnetic tapes Placing BOT/EOT markers on magnetic tape Rotating tapes and disks Inspecting and changing disk pack filters Setting up and operating tape cleaners, certifiers, and degaussers Mounting and dismounting magnetic tapes Performing cleaning, certifying, and degaussing functions Performing   emergency   shut-down/power-off procedures on equipment Setting Up, Operating, and Maintaining Equipment Be sure you and the head librarian know and can explain the steps involved in setting up and operating equipment. Be able to demonstrate the proper way to clean, certify, and degauss magnetic media. Be sure all library  personnel  know  how  to  properly  perform emergency   shut-down/power-off   procedures   on   the different types of equipment used in the library (tape cleaner,   certifier,   degausser,   and   remote   computer terminal, if used). Like   any   area   with   equipment,   some   operator maintenance  is  required  to  assure  proper  functioning and also to increase the useful life of the equipment. Operator  maintenance  on  tape  cleaners  and  certifiers should be performed on a regular basis and include the following  tasks: . Removing and replacing cleaning blades . Removing and replacing wiping tissues . Removing dirt/dust from photoelectric cells . Ensuring tape pack wheel is rotating freely Ensure   that   proper   and   regular   operator maintenance is performed on the library’s equipment. Keeping a log of when it was conducted and when it should   be   done   again   will   help.   Make   sure   outer cabinets are kept clean and free of dust. All dirt, oxide particles, and other debris should be removed from the capstans,  turrets,  tape  pack  wheel,  and  cleaning  blades. Cleaning  blades  should  not  be  allowed  to  become nicked or dull. Also see that the wiping tissues are clean, and  are  rotating  smoothly  and  automatically. CLEANING  AND  RECERTIFYING MAGNETIC  DISKS Today,   the   removable   and   interchangeable magnetic disk pack is one of the most frequently used mass  storage  media. Not  only  is  it  small,  fast,  and reliable, but with the proper care and handling, it has an almost  indefinite  life  span.  Like  magnetic  tape,  the main   enemy   of   the   disk   pack   is   dirt.   During   the manufacturing  of  the  disk  packs,  every  precaution  is taken   to   maintain   a   sterile   environment   and   a contamination-free assembly of each component of the disk.  However,  these  safeguards  do  not  entirely  prevent some   contamination   from   occurring,   and   everyday operation  continues  to  increase  the  contamination  level until data checks (read/write errors) do occur. During normal computer use, three different types of  errors  are  encountered  on  disk  packs:  temporary errors, permanent errors, and disastrous errors (head to disk contact or head crash). TEMPORARY   ERRORS   OR   SOFT   DATA CHECKS—  These  temporary  errors  are  the  direct  result of  a  minor  buildup  of  contaminants,  such  as  dust, smoke,  and  oil. PERMANENT   ERRORS   OR   HARD   DATA CHECKS—  These  permanent  errors  cause  data  to  be lost because of an excessive buildup of contaminants. As a result, the read/write heads are no longer able to access this particular area on the disk. HEAD   TO   DISK   CONTACT   OR   HEAD CRASH—  These  disastrous  errors  are  caused  when  a read/write head of the disk drive unit comes into direct contact with the surface of a disk platter. Again, this is the result of an excessive buildup of contaminants. These  errors  can  be  prevented  by  inspecting  and cleaning the disk pack. Although none of the major disk pack manufacturers recommend a regular schedule for cleaning of disk packs, they do recommend that disks be cleaned  and  inspected  when  they  have  been  exposed  to 2-19